Replace deprecated markdown-link-check action with maintained fork

Uses tcort/github-action-markdown-link-check which is actively maintained.
Same configuration and API as the deprecated gaurav-nelson version.

Author: ihabadham

.github/workflows/check-markdown-links.yml

@@ -22,7 +22,7 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Check markdown links
-        uses: gaurav-nelson/github-action-markdown-link-check@v1
+        uses: tcort/github-action-markdown-link-check@v1
         with:
           use-quiet-mode: 'yes'
           use-verbose-mode: 'no'