pin github actions by hash and update via dependabot (#8335)

* Add dependabot for github actions

* Pin actions by hash

Author: xopham

.github/dependabot.yml

@@ -0,0 +1,15 @@
+# To get started with Dependabot version updates, you'll need to specify which
+# package ecosystems to update and where the package manifests are located.
+# Please see the documentation for all configuration options:
+# https://docs.github.com/code-security/dependabot/dependabot-version-updates/configuration-options-for-the-dependabot.yml-file
+
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "monthly"
+    groups:
+      gh-actions-packages:
+        patterns:
+          - "*"

.github/workflows/update-docker-build-image.yaml

@@ -19,7 +19,7 @@ jobs:
       pull-requests: write # Required to create a pull request
     steps:
       - name: Checkout the repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@ee0669bd1cc54295c223e0bb666b733df41de1c5 # v2.7.0
       - name: Download ghcommit CLI
         run: |
           curl https://github.com/planetscale/ghcommit/releases/download/v0.1.48/ghcommit_linux_amd64 -o /usr/local/bin/ghcommit -L