Polyline doesn't recompose when points change

#### Environment details

Android API 26
com.google.maps.android:maps-compose:2.1.0

#### Steps to reproduce

1. Create a map with a MutableStateList of points
2. Use the points to draw markers and a polyline between them
3. Add functionality to add or remove points from the list
4. Observe that the markers update, but the polyline does not

#### Code example

```
@Composable
fun MapScreen(){
val waypoints = remember{ mutableStateListOf()}
Map(waypoints) {
waypoints.add(it)
}
}

@Composable
private fun Map(
waypoints: List,
modifier: Modifier = Modifier,
onMapClicked: (latlng: LatLng) -> Unit
){
GoogleMap(
modifier = modifier,
onMapClick = onMapClicked,
){
waypoints.forEach {
Marker(state = MarkerState(position = it))
}
Polyline(waypoints)
}
}
```