Use lowest supported Python version in pre-commit

We should do formatting, linting, and so on
against the lowest Python version that we intend to support.
We want to make sure we do not introduce unsupported Python syntax.
Because Python is generally backwards-compatible
this should be good enough to lint against lowest version.

.pre-commit-config.yaml

@@ -1,8 +1,7 @@
 ---
 
 default_language_version:
-  python: python3.10
-
+  python: python3.8  # This should be set to the lowest Python version that we support.
 
 repos: