Merge branch 'downgrade-a-warning-message' into dev

Author: rayluo

msal/application.py

@@ -777,7 +777,7 @@ def get_accounts(self, username=None):
             accounts = [a for a in accounts
                 if a["username"].lower() == lowercase_username]
             if not accounts:
-                logger.warning((
+                logger.debug((  # This would also happen when the cache is empty
                     "get_accounts(username='{}') finds no account. "
                     "If tokens were acquired without 'profile' scope, "
                     "they would contain no username for filtering. "