chore: pin GitHub Actions to commit SHAs

Author: nunomaduro

.github/workflows/link_check.yml

@@ -11,9 +11,9 @@ jobs:
   linkChecker:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
       - name: 🔗 Check Links
-        uses: lycheeverse/lychee-action@v2
+        uses: lycheeverse/lychee-action@8646ba30535128ac92d33dfc9133794bfdd9b411 # v2
         with:
             lycheeVersion: latest
             format: markdown