fix: harden GitHub Actions against supply chain attacks

.github/dependabot.yml

@@ -0,0 +1,10 @@
+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: /
+    schedule:
+      interval: weekly
+    groups:
+      github-actions:
+        patterns:
+          - "*"

.github/workflows/auto-merge-deps.yml

@@ -20,7 +20,7 @@ jobs:
 
     steps:
       - name: Harden Runner
-        uses: step-security/harden-runner@0634a2670c59f64b4a01f0f96f84700a4089b9f0 # v2.12.0
+        uses: step-security/harden-runner@0634a2670c59f64b4a01f0f96f84700a4088b9f0 # v2.12.0
         with:
           egress-policy: audit
 

.github/workflows/docker-publish.yml

@@ -36,17 +36,17 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@ee0669bd1cc54295c223e0bb666b733df41de1c5 # v2
 
       # Workaround: https://github.com/docker/build-push-action/issues/461
       - name: Setup Docker buildx
-        uses: docker/setup-buildx-action@79abd3f86f79a9d68a23c75a09a9a85889262adf
+        uses: docker/setup-buildx-action@79abd3f86f79a9d68a23c75a09a9a85889262adf # 79abd3f86f79a9d68a23c75a09a9a85889262adf
 
       # Login against a Docker registry except on PR
       # https://github.com/docker/login-action
       - name: Log into registry ${{ env.REGISTRY }}
         if: github.event_name != 'pull_request'
-        uses: docker/login-action@28218f9b04b4f3f62068d7b6ce6ca5b26e35336c
+        uses: docker/login-action@28218f9b04b4f3f62068d7b6ce6ca5b26e35336c # 28218f9b04b4f3f62068d7b6ce6ca5b26e35336c
         with:
           registry: ${{ env.REGISTRY }}
           username: ${{ github.actor }}
@@ -56,15 +56,15 @@ jobs:
       # https://github.com/docker/metadata-action
       - name: Extract Docker metadata
         id: meta
-        uses: docker/metadata-action@98669ae865ea3cffbcbaa878cf57c20bbf1c6c38
+        uses: docker/metadata-action@98669ae865ea3cffbcbaa878cf57c20bbf1c6c38 # 98669ae865ea3cffbcbaa878cf57c20bbf1c6c38
         with:
           images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
 
       # Build and push Docker image with Buildx (don't push on PR)
       # https://github.com/docker/build-push-action
       - name: Build and push Docker image
         id: build-and-push
-        uses: docker/build-push-action@ad44023a93711e3deb337508980b4b5e9bcdc5dc
+        uses: docker/build-push-action@ad44023a93711e3deb337508980b4b5e9bcdc5dc # ad44023a93711e3deb337508980b4b5e9bcdc5dc
         with:
           context: .
           push: ${{ github.event_name != 'pull_request' }}