chore(deps-dev): bump postcss from 8.2.5 to 8.2.6

Bumps [postcss](https://github.com/postcss/postcss) from 8.2.5 to 8.2.6.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/postcss/postcss/compare/8.2.5...8.2.6)

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

package.json

@@ -58,7 +58,7 @@
     "cypress": "^6.4.0",
     "dagre": "^0.8.5",
     "localforage": "^1.9.0",
-    "postcss": "^8.2.5",
+    "postcss": "^8.2.6",
     "postcss-cli": "^8.3.1",
     "postcss-nested": "^5.0.3",
     "prettier": "2.2.1",