Bump postcss from 8.3.6 to 8.4.5 (#117)

Bumps [postcss](https://github.com/postcss/postcss) from 8.3.6 to 8.4.5.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.3.6...8.4.5)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

package-lock.json

@@ -19,7 +19,7 @@
     "gulp-svgmin": "^4.1.0",
     "gulp-uglify": "^3.0.0",
     "plugin-error": "^1.0.1",
-    "postcss": "^8.3.6",
+    "postcss": "^8.4.5",
     "request": "^2.79.0",
     "request-promise-native": "^1.0.3",
     "sass": "^1.41.1"