Revert "[chore] Release 4.1.0 (#451)" (#452)

This reverts commit 1f53447.

Author: lahirumaramba

firebase_admin/__about__.py

@@ -14,7 +14,7 @@
 
 """About information (version, etc) for Firebase Admin SDK."""
 
-__version__ = '4.1.0'
+__version__ = '4.0.1'
 __title__ = 'firebase_admin'
 __author__ = 'Firebase'
 __license__ = 'Apache License 2.0'