Remove unused gems and yarn packages.

package.json

@@ -4,15 +4,12 @@
     "@fortawesome/fontawesome-free": "^5.11.2",
     "@rails/ujs": "^6.0.2-1",
     "@rails/webpacker": "^5.0.0",
-    "debug-loader": "^0.0.1",
     "dropzone": "^5.5.1",
-    "expose-loader": "^0.7.5",
     "hammerjs": "^2.0.8",
     "jquery": "3.5.1",
     "jquery-hotkeys": "^0.2.2",
     "jquery-ui": "^1.12.1",
     "rails-erb-loader": "^5.5.0",
-    "script-loader": "^0.7.2",
     "spark-md5": "^3.0.0",
     "stupid-table-plugin": "^1.1.3",
     "tippy.js": "^6.2.3",