fix: handle OSError from getpass.getuser on Python 3.13+

Python 3.13 changed getpass.getuser() to raise OSError instead
of KeyError when the UID has no matching username entry (e.g.
in containers with numeric UIDs). Catch both for compatibility.

Author: armorbreak001

aiomysql/connection.py

@@ -40,7 +40,7 @@
 
 try:
     DEFAULT_USER = getpass.getuser()
-except KeyError:
+except (KeyError, OSError):
     DEFAULT_USER = "unknown"