ci: Update Trivy workflow to use ubuntu-latest

Author: caspervg

.github/workflows/Trivy-secrete-scan.yaml

@@ -7,7 +7,7 @@ on:
 jobs:
   build:
     name: Build
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
       - name: Checkout code
         uses: actions/checkout@v4