fix: correct casting order for identity backfill migration

Author: siennathesane

migrations/20221208132122_backfill_email_last_sign_in_at.up.sql

@@ -9,5 +9,5 @@ update {{ index .Options "Namespace" }}.identities
     created_at = '2022-11-25' and
     updated_at = '2022-11-25' and
     provider = 'email' and
-    id = user_id::text;
+    id::text = user_id::text;
 end $$;