Bump autoprefixer from 10.4.14 to 10.4.15

Bumps [autoprefixer](https://github.com/postcss/autoprefixer) from 10.4.14 to 10.4.15.
- [Release notes](https://github.com/postcss/autoprefixer/releases)
- [Changelog](https://github.com/postcss/autoprefixer/blob/main/CHANGELOG.md)
- [Commits](postcss/autoprefixer@10.4.14...10.4.15)

---
updated-dependencies:
- dependency-name: autoprefixer
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

package.json

@@ -5,7 +5,7 @@
   "main": "gulpfile.babel.js",
   "devDependencies": {
     "@digitalservice4germany/style-dictionary": "^2.0.0",
-    "autoprefixer": "^10.4.14",
+    "autoprefixer": "^10.4.15",
     "babel-preset-env": "1.7.0",
     "babel-register": "6.26.0",
     "browser-sync": "^2.29.3",