Improve README contribution checks (#327)

* Stabilize README link checks

* Enforce README entry ordering

* Ignore CI-blocked lib.rs links

.github/workflows/linkchecker.yml

@@ -1,31 +1,46 @@
-name: Check links in the README
+name: Check the README
 
-on: [push, pull_request]
+on:
+  push:
+    branches: [main]
+    paths:
+      - README.md
+      - .github/lychee.toml
+      - .github/scripts/check-readme-order.mjs
+      - .github/workflows/linkchecker.yml
+  pull_request:
+    paths:
+      - README.md
+      - .github/lychee.toml
+      - .github/scripts/check-readme-order.mjs
+      - .github/workflows/linkchecker.yml
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: link-check-${{ github.ref }}
+  cancel-in-progress: true
 
 jobs:
   LinkChecker:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+
+      - name: Check entry order
+        if: github.event_name == 'pull_request'
+        env:
+          BASE_REF: ${{ github.base_ref }}
+        run: |
+          git fetch --no-tags --depth=1 origin "$BASE_REF"
+          git show FETCH_HEAD:README.md > "$RUNNER_TEMP/README.base.md"
+          node .github/scripts/check-readme-order.mjs "$RUNNER_TEMP/README.base.md" README.md
+
+      - name: Check links
+        uses: lycheeverse/lychee-action@e7477775783ea5526144ba13e8db5eec57747ce8 # v2.9.0
         with:
-          fetch-depth: 0
-
-      - uses: awalsh128/cache-apt-pkgs-action@latest
-        with:
-          packages: pandoc
-
-      - name: Convert Markdown to HTML format
-        run: pandoc README.md --standalone --output README.html
-
-      - name: Set up Python 3.9
-        uses: actions/setup-python@v4
-        with:
-          python-version: '3.9'
-
-      - run: pip install linkchecker --user
-
-      - name: Link Checker
-        run: linkchecker README.html --config .github/linkchecker/linkchecker.conf --file-output html/utf-8/report.html
-
-      - run: cat report.html >> ${GITHUB_STEP_SUMMARY}
-        if: success() || failure()
+          args: --config .github/lychee.toml README.md
+          lycheeVersion: v0.24.2