CI: Run mypy with --check-untyped-defs

All typing errors found with --check-untyped-defs have been fixed, so let's make mypy stricter now to avoid regressing this.

Depends on and thus includes !2425 (merged). Once it's merged, this can be undrafted and merged.

pmb/helpers/logging.py

@@ -4,21 +4,21 @@ import logging
 import os
 from pathlib import Path
 import sys
-from typing import TextIO
+from typing import Final, TextIO
 import pmb.config
 from pmb.meta import Cache
 
 logfd: TextIO
 
-CRITICAL = logging.CRITICAL
-FATAL = logging.FATAL
-ERROR = logging.ERROR
-WARNING = logging.WARNING
-WARN = logging.WARN
-INFO = logging.INFO
-DEBUG = logging.DEBUG
-NOTSET = logging.NOTSET
-VERBOSE = 5
+CRITICAL: Final[int] = logging.CRITICAL
+FATAL: Final[int] = logging.FATAL
+ERROR: Final[int] = logging.ERROR
+WARNING: Final[int] = logging.WARNING
+WARN: Final[int] = logging.WARN
+INFO: Final[int] = logging.INFO
+DEBUG: Final[int] = logging.DEBUG
+NOTSET: Final[int] = logging.NOTSET
+VERBOSE: Final[int] = 5
 
 
 class log_handler(logging.StreamHandler):