Fix some imports to avoid cycles

Import should always use the leaf modules, as importing modules from the
package usually leads to cyclic imports.

Signed-off-by: Leandro Lucarella <[email protected]>

Author: llucax

src/frequenz/sdk/timeseries/_moving_window.py

@@ -17,8 +17,7 @@
 from numpy.typing import ArrayLike
 
 from .._internal.asyncio import cancel_and_await
-from . import Sample
-from ._base_types import UNIX_EPOCH
+from ._base_types import UNIX_EPOCH, Sample
 from ._resampling import Resampler, ResamplerConfig
 from ._ringbuffer import OrderedRingBuffer
 

src/frequenz/sdk/timeseries/_resampling.py

@@ -16,8 +16,7 @@
 from typing import AsyncIterator, Callable, Coroutine, Optional, Sequence
 
 from .._internal.asyncio import cancel_and_await
-from . import Sample
-from ._base_types import UNIX_EPOCH
+from ._base_types import UNIX_EPOCH, Sample
 
 _logger = logging.getLogger(__name__)
 

src/frequenz/sdk/timeseries/_ringbuffer/buffer.py

@@ -14,8 +14,7 @@
 import numpy as np
 import numpy.typing as npt
 
-from .. import Sample
-from .._base_types import UNIX_EPOCH
+from .._base_types import UNIX_EPOCH, Sample
 
 FloatArray = TypeVar("FloatArray", List[float], npt.NDArray[np.float64])