Build/Test Tools: Pin SHA versions to the remaining 3rd party actions.

This also adds inline comments to the end of each action installed using a SHA value to make it easier to determine which version of an action is currently being used.

Follow up to [50474,50476].

Props johnbillion.
See #52625.

git-svn-id: https://develop.svn.wordpress.org/trunk@50486 602fd350-edb4-49c9-b593-d223f7449a82

.github/workflows/phpunit-tests.yml

@@ -41,7 +41,7 @@ jobs:
     steps:
       - name: Cancel previous runs of this workflow (pull requests only)
         if: ${{ github.event_name == 'pull_request' }}
-        uses: styfle/cancel-workflow-action@3d86a7cc43670094ac248017207be0295edbc31d
+        uses: styfle/cancel-workflow-action@3d86a7cc43670094ac248017207be0295edbc31d # v0.8.0
 
   # Runs the PHPUnit tests for WordPress.
   #
@@ -116,15 +116,15 @@ jobs:
           echo "PHP_FPM_GID=$(id -g)" >> $GITHUB_ENV
 
       - name: Checkout repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@5a4ac9002d0be2fb38bd78e4b4dbde5606d7042f # v2.3.4
 
       - name: Install NodeJS
-        uses: actions/setup-node@v2
+        uses: actions/setup-node@46071b5c7a2e0c34e49c3cb8a0e792e86e18d5ea # v2.1.5
         with:
           node-version: 14
 
       - name: Use cached Node modules
-        uses: actions/cache@v2
+        uses: actions/cache@26968a09c0ea4f3e233fdddbafd1166051a095f6 # v2.1.4
         env:
           cache-name: cache-node-modules
         with:
@@ -142,7 +142,7 @@ jobs:
 
       - name: Cache Composer dependencies
         if: ${{ env.COMPOSER_INSTALL == true || env.LOCAL_PHP == '8.0-fpm' }}
-        uses: actions/cache@v2
+        uses: actions/cache@26968a09c0ea4f3e233fdddbafd1166051a095f6 # v2.1.4
         env:
           cache-name: cache-composer-dependencies
         with:
@@ -237,7 +237,7 @@ jobs:
 
       - name: Checkout the WordPress Test Reporter
         if: ${{ github.repository == 'WordPress/wordpress-develop' && github.ref == 'refs/heads/master' && matrix.report }}
-        uses: actions/checkout@v2
+        uses: actions/checkout@5a4ac9002d0be2fb38bd78e4b4dbde5606d7042f # v2.3.4
         with:
           repository: 'WordPress/phpunit-test-runner'
           path: 'test-runner'