Attempt to fix hashicorp#11752. As noted [here by @chungath](hashicor…

…p#11752 (comment)), tags may not be set when the resource is new, since there's no value for arn yet

internal/service/neptune/cluster.go

@@ -699,7 +699,7 @@ func resourceClusterUpdate(d *schema.ResourceData, meta interface{}) error {
 		}
 	}
 
-	if d.HasChange("tags_all") {
+	if !d.IsNewResource() && d.HasChange("tags_all") {
 		o, n := d.GetChange("tags_all")
 
 		if err := UpdateTags(conn, d.Get("arn").(string), o, n); err != nil {