Following example of #131509 I propose to add mypy type checking in CI for tomllib.

It is fully typed already, we just need to run the CI if something changes.

Linked PRs

• gh-133117: Run mypy on tomllib in CI #133118
• [3.13] gh-133117: Run mypy on tomllib in CI (GH-133118) #133192
• gh-133117: Enable stricter mypy checks for tomllib #133206
• [3.13] gh-133117: Enable stricter mypy checks for tomllib (GH-133206) #133343