chore: update codeowners

Rename CLI team, and add PG team as owner on migrations

Author: darora

.github/CODEOWNERS

@@ -1,4 +1,4 @@
 * @supabase/backend @supabase/postgres
-migrations/ @supabase/cli @supabase/backend
+migrations/ @supabase/dev-workflows @supabase/postgres @supabase/backend
 docker/orioledb @supabase/postgres @supabase/backend
 common.vars.pkr.hcl @supabase/postgres @supabase/backend