logging.LogRecord: improve annotation for msg (#9914)

Co-authored-by: Alex Waygood <[email protected]>

Author: aminalaee

stdlib/logging/__init__.pyi

@@ -389,7 +389,7 @@ class LogRecord:
     msecs: float
     # Only created when logging.Formatter.format is called. See #6132.
     message: str
-    msg: str
+    msg: str | Any  # The runtime accepts any object, but will be a str in 99% of cases
     name: str
     pathname: str
     process: int | None