Remove timezonefinder dependency (#168)

This PR removes the `timezonefinder` dependency that was automatically
looking up timezones based on latitude/longitude coordinates in the
`Location` class.

## Problem

The `timezonefinder` dependency alone is 50M+ in size and depends on
`numpy` (another 16M+), resulting in a total bloat of 66M+ for a feature
with no known users. This large dependency size also prevents pre-built
binaries from being available for ARM platforms.

## Solution

- **Removed dependency**: Removed `timezonefinder >= 6.2.0, < 7` from
`pyproject.toml`
- **Simplified behavior**: `Location.timezone` now remains `None` unless
explicitly provided during construction
- **Removed automatic lookup**: Eliminated the `__post_init__` method
that performed timezone lookup from coordinates
- **Updated tests**: Removed timezone finder mocking and updated tests
to verify the new behavior
- **Added documentation**: Comprehensive RELEASE_NOTES.md with migration
guide

## Breaking Change

This is a **breaking change** shipped in a patch release because this
feature has no known users. The timezone lookup is no longer performed
automatically.

## Migration for Users Who Need Timezone Lookup

If timezone lookup from coordinates is needed, install `timezonefinder`
separately and implement manual lookup:

```python
# Install: pip install timezonefinder
from timezonefinder import TimezoneFinder
from zoneinfo import ZoneInfo
from frequenz.client.microgrid import Location

tf = TimezoneFinder()
tz_name = tf.timezone_at(lat=52.52, lng=13.405)
timezone = ZoneInfo(tz_name) if tz_name else None
location = Location(latitude=52.52, longitude=13.405, timezone=timezone)
```

## Before/After

**Before:**
```python
# Automatic timezone lookup
location = Location(latitude=52.52, longitude=13.405)
print(location.timezone)  # ZoneInfo('Europe/Berlin') - looked up automatically
```

**After:**
```python
# Explicit timezone only
location = Location(latitude=52.52, longitude=13.405)
print(location.timezone)  # None - no automatic lookup

# Or provide explicitly
location = Location(latitude=52.52, longitude=13.405, timezone=ZoneInfo('Europe/Berlin'))
print(location.timezone)  # ZoneInfo('Europe/Berlin')
```

Fixes #75.

Author: llucax

RELEASE_NOTES.md

@@ -2,16 +2,31 @@
 
 ## Summary
 
-<!-- Here goes a general summary of what this release is about -->
+This release removes the `timezonefinder` dependency to significantly reduce package size by 66M+ and enable ARM platform support.
+
+> [!WARNING]
+>  This is a **breaking change** shipped in a patch release because this feature has no known users.
 
 ## Upgrading
 
-<!-- Here goes notes on how to upgrade from previous versions, including deprecations and what they should be replaced with -->
+The `Location.timezone` field no longer performs automatic timezone lookup from latitude/longitude coordinates.
 
-## New Features
+```python
+# Automatic timezone lookup (no longer works)
+location = Location(latitude=52.52, longitude=13.405)
+print(location.timezone)  # Previously: ZoneInfo('Europe/Berlin'), now None
+```
 
-<!-- Here goes the main new features and examples or instructions on how to use them -->
+If you need timezone lookup from coordinates, install [`timezonefinder`](https://pypi.org/project/timezonefinder/) separately and implement manual lookup:
 
-## Bug Fixes
+```python
+# Install: pip install timezonefinder
+from timezonefinder import TimezoneFinder
+from zoneinfo import ZoneInfo
+from frequenz.client.microgrid import Location
 
-<!-- Here goes notable bug fixes that are worth a special mention or explanation -->
+tf = TimezoneFinder()
+tz_name = tf.timezone_at(lat=52.52, lng=13.405)
+timezone = ZoneInfo(tz_name) if tz_name else None
+location = Location(latitude=52.52, longitude=13.405, timezone=timezone)
+```

pyproject.toml

@@ -42,7 +42,6 @@ dependencies = [
   "frequenz-client-common >= 0.3.2, < 0.4.0",
   "grpcio >= 1.63.0, < 2",
   "protobuf >= 5.26.1, < 7",
-  "timezonefinder >= 6.2.0, < 7",
   "typing-extensions >= 4.13.0, < 5",
 ]
 dynamic = ["version"]

src/frequenz/client/microgrid/_metadata.py

@@ -7,9 +7,6 @@
 from zoneinfo import ZoneInfo
 
 from frequenz.client.common.microgrid import MicrogridId
-from timezonefinder import TimezoneFinder
-
-_timezone_finder = TimezoneFinder()
 
 
 @dataclass(frozen=True, kw_only=True)
@@ -23,23 +20,7 @@ class Location:
     """The longitude of the microgrid in degree."""
 
     timezone: ZoneInfo | None = None
-    """The timezone of the microgrid.
-
-    If not passed during construction (or `None` is passed), and there is a `longitude`
-    and `latitude`, then the timezone wil be looked up in a database based on the
-    coordinates. This lookup could fail, in which case the timezone will still be
-    `None`.
-    """
-
-    def __post_init__(self) -> None:
-        """Initialize the timezone of the microgrid."""
-        if self.latitude is None or self.longitude is None or self.timezone is not None:
-            return
-
-        timezone = _timezone_finder.timezone_at(lat=self.latitude, lng=self.longitude)
-        if timezone:
-            # The dataclass is frozen, so it needs to use __setattr__ to set the timezone.
-            object.__setattr__(self, "timezone", ZoneInfo(key=timezone))
+    """The timezone of the microgrid."""
 
 
 @dataclass(frozen=True, kw_only=True)

tests/test_metadata.py

@@ -3,8 +3,6 @@
 
 """Tests for the microgrid metadata types."""
 
-from collections.abc import Iterator
-from unittest.mock import MagicMock, patch
 from zoneinfo import ZoneInfo
 
 import pytest
@@ -13,59 +11,20 @@
 from frequenz.client.microgrid import Location, Metadata
 
 
-@pytest.fixture
-def timezone_finder() -> Iterator[MagicMock]:
-    """Return a mock timezone finder."""
-    with patch(
-        "frequenz.client.microgrid._metadata._timezone_finder", autospec=True
-    ) as mock_timezone_finder:
-        yield mock_timezone_finder
-
-
-@pytest.mark.parametrize(
-    "latitude, longitude, timezone",
-    [
-        (None, None, None),
-        (52.52, None, None),
-        (None, 13.405, None),
-        (None, None, ZoneInfo(key="UTC")),
-        (52.52, None, ZoneInfo(key="UTC")),
-        (None, 13.405, ZoneInfo(key="UTC")),
-        (52.52, 13.405, ZoneInfo(key="UTC")),
-    ],
-    ids=str,
-)
-def test_location_timezone_not_looked_up_if_not_possible_or_necessary(
-    timezone_finder: MagicMock,
+@pytest.mark.parametrize("latitude", [None, 52.52], ids=str)
+@pytest.mark.parametrize("longitude", [None, 13.405], ids=str)
+@pytest.mark.parametrize("timezone", [None, ZoneInfo(key="UTC")], ids=str)
+def test_location_initialization(
     latitude: float | None,
     longitude: float | None,
     timezone: ZoneInfo | None,
 ) -> None:
-    """Test the location timezone is not looked up if is not necessary or possible."""
-    timezone_finder.timezone_at.return_value = "Europe/Berlin"
-
+    """Test location initialization with different combinations of parameters."""
     location = Location(latitude=latitude, longitude=longitude, timezone=timezone)
 
     assert location.latitude == latitude
     assert location.longitude == longitude
     assert location.timezone == timezone
-    timezone_finder.timezone_at.assert_not_called()
-
-
-@pytest.mark.parametrize("timezone", [None, "Europe/Berlin"], ids=str)
-def test_location_timezone_lookup(
-    timezone_finder: MagicMock, timezone: str | None
-) -> None:
-    """Test the location timezone is looked up if not provided and there is enough info."""
-    timezone_finder.timezone_at.return_value = timezone
-
-    location = Location(latitude=52.52, longitude=13.405)
-
-    if timezone is None:
-        assert location.timezone is None
-    else:
-        assert location.timezone == ZoneInfo(key=timezone)
-    timezone_finder.timezone_at.assert_called_once_with(lat=52.52, lng=13.405)
 
 
 def test_metadata_initialization() -> None:
@@ -81,11 +40,12 @@ def test_metadata_initialization() -> None:
     assert metadata.microgrid_id == microgrid_id
     assert metadata.location is None
 
-    # Test with only location
+    # Test with only location - timezone should be None even with lat/lng
     location = Location(latitude=52.52, longitude=13.405)
     metadata = Metadata(location=location)
     assert metadata.microgrid_id is None
     assert metadata.location == location
+    assert metadata.location.timezone is None
 
     # Test with both parameters
     metadata = Metadata(microgrid_id=microgrid_id, location=location)