js: replace jquery-ujs with @rails/ujs.

package.json

@@ -2,6 +2,7 @@
   "license": "MIT",
   "dependencies": {
     "@fortawesome/fontawesome-free": "^5.11.2",
+    "@rails/ujs": "^6.0.2-1",
     "@rails/webpacker": "^4.0.0",
     "debug-loader": "^0.0.1",
     "dropzone": "^5.5.1",
@@ -9,7 +10,6 @@
     "hammerjs": "^2.0.8",
     "jquery-hotkeys": "^0.2.2",
     "jquery-ui": "^1.12.1",
-    "jquery-ujs": "^1.2.2",
     "qtip2": "^3.0.3",
     "rails-erb-loader": "^5.5.0",
     "script-loader": "^0.7.2",