Test fix

tests/integration.rs

@@ -96,6 +96,10 @@ impl MetadataProvider for MockProvider {
             },
         ])
     }
+
+    async fn get_artist_release_groups(&self, _artist_mbid: &str) -> TagResult<Vec<shanty_tag::provider::ReleaseGroupEntry>> {
+        Ok(vec![])
+    }
 }
 
 #[tokio::test]