chore(deps): update dependency github-markdown-css to v5.6.1

Author: renovate[bot]

public/index.html

@@ -7,7 +7,7 @@
         <title>App Center</title>
         <link
           rel="stylesheet"
-          href="https://cdnjs.cloudflare.com/ajax/libs/github-markdown-css/5.5.1/github-markdown.min.css"
+          href="https://cdnjs.cloudflare.com/ajax/libs/github-markdown-css/5.6.1/github-markdown.min.css"
         />
         <style>
           @media (prefers-color-scheme: dark) {