Upgrade build tooling to latest major versions (npm)

- Babel loader v9 (Node version, drop support for Webpack 4) https://github.com/babel/babel-loader/releases/tag/v9.0.0
- Copy webpack plugin (Node version only) https://github.com/webpack-contrib/copy-webpack-plugin/releases/tag/v11.0.0 & https://github.com/webpack-contrib/copy-webpack-plugin/releases/tag/v12.0.0
- Expose loader (Node version only) https://github.com/webpack-contrib/expose-loader/blob/master/CHANGELOG.md
- Postcss loader (Node version only) https://github.com/webpack-contrib/postcss-loader/releases/tag/v7.0.0 & https://github.com/webpack-contrib/postcss-loader/releases/tag/v8.0.0
- Sass loader (Node version, emits warnings by default) https://github.com/webpack-contrib/sass-loader/blob/master/CHANGELOG.md
- Webpack CLI (Node version, some other breaking changes, dropping Webpack 4 support) https://github.com/webpack/webpack-cli/releases/tag/webpack-cli%405.0.0

package.json

@@ -74,8 +74,8 @@
     "@wagtail/eslint-config-wagtail": "^0.4.0",
     "@wagtail/stylelint-config-wagtail": "^0.8.0",
     "autoprefixer": "^10.4.17",
-    "babel-loader": "^8.2.5",
-    "copy-webpack-plugin": "^10.2.4",
+    "babel-loader": "^9.1.3",
+    "copy-webpack-plugin": "^12.0.2",
     "css-loader": "^6.10.0",
     "cssnano": "^5.1.15",
     "enzyme": "^3.11.0",
@@ -83,18 +83,18 @@
     "enzyme-to-json": "^3.6.2",
     "eslint": "^8.56.0",
     "eslint-plugin-storybook": "^0.6.15",
-    "expose-loader": "^3.1.0",
+    "expose-loader": "^5.0.0",
     "gettext-extractor": "^3.8.0",
     "jest": "^29.7.0",
     "jest-environment-jsdom": "^29.7.0",
     "mini-css-extract-plugin": "^2.8.0",
     "postcss": "^8.4.35",
-    "postcss-loader": "^6.2.1",
+    "postcss-loader": "^8.1.0",
     "prettier": "^3.1.0",
     "react-test-renderer": "^16.14.0",
     "redux-mock-store": "^1.5.4",
     "sass": "^1.70.0",
-    "sass-loader": "^12.4.0",
+    "sass-loader": "^14.1.0",
     "storybook": "^7.6.14",
     "storybook-django": "^0.5.1",
     "stylelint": "^15.11.0",
@@ -104,7 +104,7 @@
     "ts-loader": "^9.5.1",
     "typescript": "^5.3.3",
     "webpack": "^5.90.1",
-    "webpack-cli": "^4.9.2"
+    "webpack-cli": "^5.1.4"
   },
   "dependencies": {
     "@hotwired/stimulus": "^3.2.2",