Fix displaying the installed version of Django-Jazzmin in the UI.

Since we changed our CD process and now will automatically generate test
builds (#550), the version in the `__init__` file now needs to be
updated to stop it from being hardcoded. As in development the version
is now set to 0.0.0 in the `pyproject.toml` file, we need to get the
version dyanmically. We can call the package manager to check which
version of `django-jazzmin` was installed. This sadly does vary
depending on which version of Python is installed - support for these
older versions are soon to be dropped.

jazzmin/__init__.py

@@ -1,6 +1,19 @@
 import django
+import sys
+
+# We automatically grab the version of `django-jazzmin` from the package manager instead of
+# hard coding it. The method for determining the version changed since PY3.8. N.B. For
+# development versions of `django-jazzmin`, the version will be 0.0.0 (see pyproject.toml) as it's
+# not technically installed.
+if sys.version_info >= (3, 8):
+    from importlib.metadata import version as package_version
+
+    version = package_version("django-jazzmin")
+else:
+    import pkg_resources
+
+    version = pkg_resources.get_distribution("django-jazzmin").version
 
-version = "2.6.1"
 
 if django.VERSION < (3, 2):
     default_app_config = "jazzmin.apps.JazzminConfig"

pyproject.toml

@@ -146,3 +146,10 @@ commands =
 [build-system]
 requires = ["poetry>=0.12"]
 build-backend = "poetry.masonry.api"
+
+
+[[tool.mypy.overrides]]
+module = [
+    "pkg_resources.*",
+]
+ignore_missing_imports = true