Fix the controller and webhook images to use stable alpine

tektoncd#7356 fixed the images used
by Tekton workloads, but not the controller ones.
Controllers do not support windows, and do not use the combined
image, so the default base image has to be updated too.

Signed-off-by: Andrea Frittoli <andrea.frittoli@uk.ibm.com>

tekton/publish.yaml

@@ -104,7 +104,7 @@ spec:
       # NOTE: Make sure this list of images to use the combined base image is in sync with what's in test/presubmit-tests.sh's 'ko_resolve' function.
       cat <<EOF > /workspace/.ko.yaml
       # This matches the value configured in .ko.yaml
-      defaultBaseImage: cgr.dev/chainguard/static
+      defaultBaseImage: cgr.dev/chainguard/static@sha256:67a1b00e0134e2b3a614c7198a26f7deed9d11b7acad4d52c79c0cfd47a2eae7
       baseImageOverrides:
         # Use the combined base image for images that should include Windows support.
         $(params.package)/cmd/entrypoint: ${COMBINED_BASE_IMAGE}