Further de-linting of zoneinfo module (#20499)

* Remove unused imports in zoneinfo

* Remove unused variables in zoneinfo

* Remove else after raise
diff --git a/Lib/zoneinfo/_zoneinfo.py b/Lib/zoneinfo/_zoneinfo.py
index b207dd3..7b1718a 100644
--- a/Lib/zoneinfo/_zoneinfo.py
+++ b/Lib/zoneinfo/_zoneinfo.py
@@ -4,7 +4,7 @@
 import functools
 import re
 import weakref
-from datetime import datetime, timedelta, timezone, tzinfo
+from datetime import datetime, timedelta, tzinfo
 
 from . import _common, _tzpath