Use importlib instead of pkg_resources for version

Author: mdpiper

docs/requirements.txt

@@ -1,3 +1,4 @@
 sphinx
 recommonmark
 pandoc
+importlib-metadata

docs/source/conf.py

@@ -15,7 +15,7 @@
 # sys.path.insert(0, os.path.abspath('.'))
 import datetime
 
-import pkg_resources
+from importlib.metadata import version as package_version
 
 # The master toctree document.
 master_doc = "index"
@@ -25,7 +25,7 @@
 
 project = "bmi-topography"
 author = "Community Surface Dynamics Modeling System"
-version = pkg_resources.get_distribution("bmi_topography").version
+version = package_version("bmi_topography")
 release = version
 this_year = datetime.date.today().year
 copyright = f"{this_year}, {author}"