Do not use pkg_resources to get version anymore

Calling `get_distribution` has a significant runtime cost.  This
commit avoid this call by leveraging the write_to feature of
setuptools_scm.

Author: amorison

.gitignore

@@ -4,6 +4,7 @@ __pycache__/
 .coverage
 .tox
 stagpy.egg-info/
+/stagpy/_version.py
 /stagpy_git/
 docs/_build/
 docs/_static/

pyproject.toml

@@ -3,6 +3,7 @@ requires = ["setuptools>=51", "setuptools_scm>=6.3.2", "wheel"]
 build-backend = "setuptools.build_meta"
 
 [tool.setuptools_scm]
+write_to = "stagpy/_version.py"
 
 [tool.mypy]
 disallow_untyped_defs = true

stagpy/__init__.py

@@ -24,7 +24,6 @@
 import sys
 import typing
 
-from pkg_resources import get_distribution, DistributionNotFound
 from setuptools_scm import get_version
 from loam.manager import ConfigurationManager
 
@@ -105,9 +104,10 @@ def load_mplstyle() -> None:
 try:
     __version__ = get_version(root='..', relative_to=__file__)
 except LookupError:
-    __version__ = get_distribution('stagpy').version
-except (DistributionNotFound, ValueError):
-    __version__ = 'unknown'
+    try:
+        from ._version import version as __version__
+    except ImportError:
+        __version__ = "unknown"
 
 _CONF_FILES = ([config.CONFIG_FILE, config.CONFIG_LOCAL]
                if not ISOLATED else [])