chore(deps-dev): bump postcss from 8.1.6 to 8.3.6 (#847)

Bumps [postcss](https://github.com/postcss/postcss) from 8.1.6 to 8.3.6.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.1.6...8.3.6)

---
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

@@ -44,7 +44,7 @@
     "merge-stream": "2.0.0",
     "mocha": "8.2.1",
     "mocha.parallel": "0.15.6",
-    "postcss": "8.1.6",
+    "postcss": "8.3.6",
     "sharp": "0.26.2",
     "xo": "0.30.0"
   },