Use importlib.metadata instead of pkg_resources

pkg_resources is deprecated and emits warning messages.

Fixes jazzband#131

Author: jnns

setup.py

@@ -13,7 +13,7 @@
     long_description_content_type="text/x-rst",
     license="MIT license",
     python_requires=">=3.7",
-    requires=["django (>=2.2)"],
+    requires=["django (>=2.2)", "importlib_metadata;python_version<'3.8'"],
     packages=["widget_tweaks", "widget_tweaks.templatetags"],
     classifiers=[
         "Development Status :: 5 - Production/Stable",

widget_tweaks/__init__.py

@@ -1,7 +1,6 @@
-from pkg_resources import get_distribution, DistributionNotFound
-
 try:
-    __version__ = get_distribution("django-widget-tweaks").version
-except DistributionNotFound:
-    # package is not installed
-    __version__ = None
+    from importlib.metadata import version
+except ImportError:
+    from importlib_metadata import version
+
+__version__ = version("django-widget-tweaks")