Add links checker

Author: trasher

.github/workflows/lint.yml

@@ -1,4 +1,4 @@
-name: Lint Galette Website
+name: Check dead links
 on:
   push:
     branches:
@@ -29,4 +29,11 @@ jobs:
       - name: HTML5Validator
         uses: Cyb3r-Jak3/html5validator-action@v8.0.0
         with:
-          root: public/
+          root: public/
+      - name: Link Checker
+        id: lychee
+        uses: lycheeverse/lychee-action@v2
+        with:
+          # Check all Markdown, HTML and reStructuredText files in repo (default)
+          args: --verbose --no-progress './public/**/*.html' -b https://galette.eu/
+          fail: true