Bump vue-loader from 15.2.6 to 15.4.2 in /apps/oauth2

Bumps [vue-loader](https://github.com/vuejs/vue-loader) from 15.2.6 to 15.4.2.
- [Release notes](https://github.com/vuejs/vue-loader/releases)
- [Changelog](https://github.com/vuejs/vue-loader/blob/master/CHANGELOG.md)
- [Commits](https://github.com/vuejs/vue-loader/commits)

Signed-off-by: dependabot[bot] <support@dependabot.com>

apps/oauth2/package.json

@@ -22,7 +22,7 @@
   "devDependencies": {
     "css-loader": "^1.0.0",
     "file-loader": "^1.1.11",
-    "vue-loader": "^15.2.6",
+    "vue-loader": "^15.4.2",
     "vue-template-compiler": "^2.5.17",
     "webpack": "^4.17.2",
     "webpack-cli": "^3.1.0",