Do not calculate coverage on __version__

Signed-off-by: Alexey Stepanov <penguinolog@gmail.com>

Author: penguinolog

threaded/__init__.py

@@ -23,9 +23,9 @@
 from ._threaded import Threaded, threaded
 from ._threadpooled import ThreadPooled, threadpooled
 
-try:
+try:  # pragma: no cover
     __version__ = pkg_resources.get_distribution(__name__).version
-except pkg_resources.DistributionNotFound:
+except pkg_resources.DistributionNotFound:  # pragma: no cover
     # package is not installed, try to get from SCM
     try:
         import setuptools_scm  # type: ignore