Bump postcss from 8.5.4 to 8.5.5 in the postcss group

Bumps the postcss group with 1 update: [postcss](https://github.com/postcss/postcss).


Updates `postcss` from 8.5.4 to 8.5.5
- [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/8.5.4...8.5.5)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.5
  dependency-type: direct:development
  update-type: version-update:semver-patch
  dependency-group: postcss
...

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

package-lock.json

@@ -17669,14 +17669,6 @@
         "node": ">= 0.8"
       }
     },
-    "node_modules/on-headers": {
-      "version": "1.0.2",
-      "resolved": "https://registry.npmjs.org/on-headers/-/on-headers-1.0.2.tgz",
-      "integrity": "sha512-pZAE+FJLoyITytdqK0U5s+FIpjN0JP3OzFi/u8Rx+EV5/W+JTWGXG8xFzevE7AjBfDqHv/8vL8qQsIhHnqRkrA==",
-      "engines": {
-        "node": ">= 0.8"
-      }
-    },
     "node_modules/once": {
       "version": "1.4.0",
       "resolved": "https://registry.npmjs.org/once/-/once-1.4.0.tgz",
@@ -18459,9 +18451,9 @@
       }
     },
     "node_modules/postcss": {
-      "version": "8.5.4",
-      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.5.4.tgz",
-      "integrity": "sha512-QSa9EBe+uwlGTFmHsPKokv3B/oEMQZxfqW0QqNCyhpa6mB1afzulwn8hihglqAb2pOw+BJgNlmXQ8la2VeHB7w==",
+      "version": "8.5.6",
+      "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.5.6.tgz",
+      "integrity": "sha512-3Ybi1tAuwAP9s0r1UQ2J4n5Y0G05bJkpUIO0/bI9MhwmD70S5aTWbXGBwxHrelT+XM1k6dM0pk+SwNkpTRN7Pg==",
       "funding": [
         {
           "type": "opencollective",