Bump postcss-markdown from 1.2.0 to 1.3.0 in the postcss group

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


Updates `postcss-markdown` from 1.2.0 to 1.3.0
- [Release notes](https://github.com/ota-meshi/postcss-markdown/releases)
- [Commits](ota-meshi/postcss-markdown@v1.2.0...v1.3.0)

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

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

package.json

@@ -90,7 +90,7 @@
     "multimatch": "^7.0.0",
     "nunjucks": "^3.2.4",
     "outdent": "^0.8.0",
-    "postcss-markdown": "^1.2.0",
+    "postcss-markdown": "^1.3.0",
     "postcss-scss": "^4.0.9",
     "prettier": "^3.4.2",
     "puppeteer": "^23.10.4",