Pin GitHub Actions to full-length commit SHAs (#8896)

* Pin GitHub Actions to full-length commit SHAs

* Attestation commit

---------

Co-authored-by: Alex Ross <38270282+alexr00@users.noreply.github.com>

Author: danfiedler-msft

.github/dependabot.yml

@@ -0,0 +1,11 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    groups:
+      github-actions:
+        patterns: ["*"]
+    schedule:
+      interval: "weekly"
+    cooldown:
+      default-days: 7

.github/workflows/copilot-setup-steps.yml

@@ -23,10 +23,10 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4.4.0
 
       - name: Set up Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
         with:
           node-version: "20"
           cache: "npm"