Add modmenu to dependencies (fixes #2)

src/main/resources/fabric.mod.json

@@ -30,6 +30,7 @@
   ],
   "depends": {
     "minecraft": "1.16.3",
-    "fabricloader": ">=0.7.4"
+    "fabricloader": ">=0.7.4",
+    "modmenu": "*"
   }
 }