Try to force update of base image.

The current python:3-alpine image passes security checks, but it's
not passing in ci.

Author: rouilj

.github/workflows/anchore.yml

@@ -37,6 +37,8 @@ jobs:
     steps:
     - name: Checkout the code
       uses: actions/checkout@v3
+    - name: Update base image
+      run: docker pull python:3-alpine
     - name: Build the Docker image
       run: docker build . --file scripts/Docker/Dockerfile --tag localbuild/testimage:latest
     - name: Run the Anchore scan action itself with GitHub Advanced Security code scanning integration enabled