fix: derive __version__ from package metadata

__version__ was hardcoded to 0.1.0 and never bumped (it isn't in
release-please's extra-files), so eia.__version__ misreported the
installed version. Read it from importlib.metadata instead, with a
source-checkout fallback.

Author: jsulopzs

src/eia/__init__.py

@@ -4,9 +4,14 @@
 A Python client for interacting with the U.S. Energy Information Administration (EIA) API.
 """
 
+from importlib.metadata import PackageNotFoundError, version as _version
+
 from .client import EIAClient, EIAError
 from .cache import CacheConfig
 from . import catalog
 
-__version__ = "0.1.0"
+try:
+    __version__ = _version("python-eia")
+except PackageNotFoundError:  # not installed (e.g. running from a source checkout)
+    __version__ = "0.0.0+unknown"
 __all__ = ["EIAClient", "EIAError", "CacheConfig", "catalog"]