Use setuptools' pkg_resources for extracting setuptools_scm version info

As works both in pkg's init.py and in Sphinx config.

docs/source/conf.py

@@ -19,7 +19,7 @@
 #
 import os
 import sys
-sys.path.insert(0, os.path.abspath('../..'))
+#sys.path.insert(0, os.path.abspath('../..'))
 #sys.path.insert(0, os.path.abspath('../../mumot'))
 
 
@@ -65,12 +65,11 @@
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the
 # built documents.
-#
-# The short X.Y version.
 import mumot
-version = mumot.__version__
-# The full version, including alpha/beta/rc tags.
-release = mumot.__version__
+from pkg_resources import get_distribution
+release = get_distribution('mumot').version
+# for example take major/minor
+version = '.'.join(release.split('.')[:2])
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.

mumot/__init__.py

@@ -33,11 +33,11 @@
 
 # Set package version.
 # NB with Python 3.8 we could use importlib.metadata (in std lib) instead.
-from importlib_metadata import version, PackageNotFoundError
+from pkg_resources import get_distribution, DistributionNotFound
 try:
-    __version__ = version(__name__)
-except PackageNotFoundError:
-    # package is not installed
+    __version__ = get_distribution(__name__).version
+except DistributionNotFound:
+     # package is not installed
     pass
 
 # Import the functions and classes we wish to export i.e. the public API

setup.cfg

@@ -29,7 +29,7 @@ packages = find:
 install_requires =
     antlr4-python3-runtime >=4.7,<4.8
     graphviz
-    importlib_metadata  # needed with Python <3.8 for finding pkg version at runtime (with 3.8 can use importlib.metadata)
+    setuptools  # used with Python <3.8 for finding pkg version at runtime (with 3.8 could use importlib.metadata)
     ipykernel <4.7  # needed so no duplicate figures when wiggle ipywidgets
     ipython
     ipywidgets