GH Actions: "pin" all action runners

.github/dependabot.yml

@@ -14,3 +14,11 @@ updates:
       prefix: "GH Actions:"
     labels:
       - "Type: chores/QA"
+    cooldown:
+      semver-major-days: 10
+    groups:
+      action-runners:
+        applies-to: version-updates
+        update-types:
+          - "minor"
+          - "patch"

.github/workflows/ci.yml

@@ -25,10 +25,10 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
 
       - name: Install PHP
-        uses: shivammathur/setup-php@v2
+        uses: shivammathur/setup-php@ec406be512d7077f68eed36e63f4d91bc006edc4 # master
         with:
           php-version: 'latest'
           coverage: none
@@ -44,7 +44,7 @@ jobs:
 
       # Validate the xml file.
       - name: Validate against schema
-        uses: phpcsstandards/xmllint-validate@v1
+        uses: phpcsstandards/xmllint-validate@0fd9c4a9046055f621fca4bbdccb8eab1fd59fdc # v1.0.1
         with:
           pattern: "PHPCSDev/ruleset.xml"
           xsd-file: "vendor/squizlabs/php_codesniffer/phpcs.xsd"

.github/workflows/label-merge-conflicts.yml

@@ -21,7 +21,7 @@ jobs:
 
     steps:
       - name: Check PRs for merge conflicts
-        uses: eps1lon/actions-label-merge-conflict@v3
+        uses: eps1lon/actions-label-merge-conflict@1df065ebe6e3310545d4f4c4e862e43bdca146f0 # v3.0.3
         with:
           dirtyLabel: "Status: has merge conflict"
           repoToken: ${{ secrets.GITHUB_TOKEN }}