🧪 Bump MyPy Python to 3.9 @ pre-commit config

The `pre-commit.ci` service dropped support for Python 3.8 as it's
gone EOL. This change makes the check runnable again. It is suboptimal
as we haven't yet dropped support for Python 3.8. #2144 will address
the underlying issue more thoroughly.

Resolves #2133.

Co-Authored-By: Sviatoslav Sydorenko <[email protected]>

Author: Mr-Sunglasses

.pre-commit-config.yaml

@@ -35,7 +35,7 @@ repos:
           - build==1.0.0
           - pyproject_hooks==1.0.0
           - pytest==7.4.2
-        language_version: python3.8
+        language_version: python3.9
   - repo: https://github.com/PyCQA/bandit
     rev: 1.7.8
     hooks: