Fixed class loader not closing when deleting mods

core/src/mindustry/mod/ClassLoaderCloser.java

@@ -0,0 +1,13 @@
+package mindustry.mod;
+
+import java.net.*;
+
+public class ClassLoaderCloser{
+
+    /** Workaround for the close() method not being available on Android. */
+    public static void close(ClassLoader loader) throws Exception{
+        if(loader instanceof URLClassLoader u){
+            u.close();
+        }
+    }
+}