fix: pin setup-trivy to v0.2.6 by SHA (GHSA-69fq-xp46-6x23) (#5427)

Author: louiseschmidtgen

.github/workflows/build-snap.yml

@@ -158,7 +158,7 @@ jobs:
         run: |
           mkdir -p sarifs
       - name: Install Trivy vulnerability scanner
-        uses: aquasecurity/setup-trivy@v0.2.2
+        uses: aquasecurity/setup-trivy@3fb12ec12f41e471780db15c232d5dd185dcb514 # v0.2.6
       - name: Run Trivy vulnerability scanner on codebase
         run: |
           trivy fs . --format sarif --severity CRITICAL > sarifs/trivy-microk8s-repo-scan--results.sarif