Bump postcss from 8.1.6 to 8.2.10 (#446)

Bumps [postcss](https://github.com/postcss/postcss) from 8.1.6 to 8.2.10.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.1.6...8.2.10)

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

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

package.json

@@ -77,7 +77,7 @@
     "mobx-react": "6.3.1",
     "mocha": "8.2.1",
     "nightmare": "3.0.2",
-    "postcss": "8.1.6",
+    "postcss": "8.2.10",
     "postcss-icss-values": "2.0.2",
     "postcss-loader": "4.0.4",
     "preact": "10.5.5",