Update GitHub Actions workflows.

.github/workflows/command-dispatch.yml

@@ -44,10 +44,10 @@ jobs:
     name: command-dispatch-for-testing
     steps:
     - name: Checkout Repo
-      uses: actions/checkout@v4
+      uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       with:
         lfs: true
-    - uses: peter-evans/slash-command-dispatch@v2
+    - uses: peter-evans/slash-command-dispatch@13bc09769d122a64f75aa5037256f6f2d78be8c4 # v4.0.0
       with:
         token: ${{ secrets.PULUMI_BOT_TOKEN }}
         reaction-token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/pull-request.yml

@@ -41,11 +41,11 @@ jobs:
     name: comment-on-pr
     steps:
     - name: Checkout Repo
-      uses: actions/checkout@v4
+      uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
       with:
         lfs: true
     - name: Comment PR
-      uses: thollander/actions-comment-pull-request@v2
+      uses: thollander/actions-comment-pull-request@fabd468d3a1a0b97feee5f6b9e499eab0dd903f6 # v2.5.0
       with:
         message: >
           PR is now waiting for a maintainer to run the acceptance tests.