core: fix source flow_manager not resuming flow when linking (#10436)

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

authentik/core/sources/flow_manager.py

@@ -212,7 +212,7 @@ class SourceFlowManager:
 
     def _prepare_flow(
         self,
-        flow: Flow,
+        flow: Flow | None,
         connection: UserSourceConnection,
         stages: list[StageView] | None = None,
         **kwargs,
@@ -309,6 +309,8 @@ class SourceFlowManager:
         # When request isn't authenticated we jump straight to auth
         if not self.request.user.is_authenticated:
             return self.handle_auth(connection)
+        if SESSION_KEY_OVERRIDE_FLOW_TOKEN in self.request.session:
+            return self._prepare_flow(None, connection)
         connection.save()
         Event.new(
             EventAction.SOURCE_LINKED,