Fix clean_expired import for clean_oauth_tokens task

CHANGELOG.rst

@@ -14,6 +14,7 @@ Fixed
 
 * Migration added in 2.7.2 did not work in all scenarios
 * [Dev] Field change tracking API for Person was broken in 2.7.2
+* [OAuth] Automatic clean-up of expired OAuth tokens could fail
 * Add missing documentation
 
 `2.7.2`_ - 2022-01-31

aleksis/core/tasks.py

@@ -45,6 +45,6 @@ def backup_data() -> None:
 @app.task(run_every=timedelta(days=1))
 def clear_oauth_tokens():
     """Clear expired OAuth2 tokens."""
-    from oauth2_provider.models import clear_tokens  # noqa
+    from oauth2_provider.models import clear_expired  # noqa
 
-    return clear_tokens()
+    return clear_expired()