fix(stuart): migrate from pkg_resources to importlib.metadata

Cf. https://setuptools.pypa.io/en/latest/pkg_resources.html.

src/__init__.py

@@ -17,11 +17,10 @@
 
 import logging
 import pkgutil
-
-import pkg_resources
+from importlib.metadata import version
 
 __app_name__ = __name__
-__version__ = pkg_resources.require(__app_name__)[0].version
+__version__ = version(__app_name__)
 
 # configure module-level logging
 logger = logging.getLogger(__name__)