Replace Awesome Bot with Lychee for link checking

- Switch from awesome_bot (Ruby 2.7, unmaintained) to lychee (Rust, actively maintained)
- Run on pull requests as well as pushes to master, so broken links are caught before merge
- Expand whitelist with domains known to block crawlers: leanpub.com, jetbrains.com, wiki.php.net, zend.com, nusphere.com
- Accept HTTP 429 (rate limited) as non-failure to avoid false positives
- Upload lychee results as an artifact on failure

.github/workflows/awesomebot.yml

@@ -1,26 +0,0 @@
-name: Awesome Bot
-on:
-  push:
-    branches:
-      - master
-
-jobs:
-  build:
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v4
-    - uses: ruby/setup-ruby@v1
-      with:
-        ruby-version: '2.7'
-
-    - name: Install Awesome Bot
-      run: gem install awesome_bot
-
-    - name: Run Awesome Bot
-      run: awesome_bot README.md --request-delay 1 --allow-dupe --white-list oreilly.com,youtube.com,new.drupal.org
-
-    - uses: actions/upload-artifact@v4
-      if: failure()
-      with:
-        name: ab-results
-        path: ab-results-README.md-filtered.json

.github/workflows/ci.yml

@@ -0,0 +1,41 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+
+jobs:
+  linkcheck:
+    name: Link Check
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Check links
+        uses: lycheeverse/lychee-action@v2
+        with:
+          args: >-
+            --verbose
+            --no-progress
+            --accept 200,206,429
+            --timeout 20
+            --exclude "leanpub\.com"
+            --exclude "oreilly\.com"
+            --exclude "youtube\.com"
+            --exclude "jetbrains\.com"
+            --exclude "wiki\.php\.net"
+            --exclude "new\.drupal\.org"
+            --exclude "zend\.com"
+            --exclude "nusphere\.com"
+            README.md
+          fail: true
+
+      - uses: actions/upload-artifact@v4
+        if: failure()
+        with:
+          name: lychee-results
+          path: lychee/out.md