SuperClusterAlgorithm: change in marker position does not update the clustering

#### Environment details

OS type and version: /
Library version: 2.0.15

#### Steps to reproduce

1. Setup a map with markers and marker clusterer (eg. the sample found at https://developers.google.com/maps/documentation/javascript/marker-clustering)
2. Update the position of a marker using `markerObject.setPosition(new google.maps.LatLng(lat, lng));` in a way that should change the clustering
3. Trigger a rerender on the clusterer: `clusterer.render()` -> NOK, clustering is not updated, expected the clustering to update

I did some debugging and found that the issue is here: https://github.com/googlemaps/js-markerclusterer/blob/2ac332afb468a2346ee1a56976fa2bd2c8e89291/src/algorithms/supercluster.ts#L52-L59

Because `this.markers` and `input.markers` contains the same marker instances, `equal(input.markers, this.markers)` is always `true` even though a copy of the array is made. The change detection will only detect if markers are added or removed.