init cheaper action for PRs

Author: lukruh

.github/workflows/link-checker-pr.yml

@@ -0,0 +1,29 @@
+name: Check Links
+
+on:
+  push:
+    branches:
+      - link_checker  # TODO: change to main to after testing
+  workflow_dispatch:
+
+jobs:
+  linkChecker:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+
+      - name: Link Checker
+        id: lychee
+        uses: lycheeverse/lychee-action@v2
+        with:
+          fail: false
+          # args to check source files without building
+          # './**/*.md' './**/*.html' './**/*.rst'
+          args: >
+            ./_site/**/*.html
+            --max-concurrency 1 --no-progress 
+            --accept '100..=103,200..=399, 429'
+            --exclude https://doi.org/
+        env:
+          # avoid 429 errors (too many requests) on github.com api requests
+          GITHUB_TOKEN: ${{secrets.TOKEN_GITHUB}}