Use markdown-link-check 1.0.14

To fix HTTP 503 errors I shouldn't be getting.

This change fixed it in three other repos:

- EliahKagan/userstyles#1
- EliahKagan/muntineer#2
- EliahKagan/fps#1

.github/workflows/markdown-links.yml

@@ -14,4 +14,4 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v3
-    - uses: gaurav-nelson/github-action-markdown-link-check@v1
+    - uses: gaurav-nelson/github-action-markdown-link-check@v1.0.14