fix: sanitize Docker image tags to remove invalid characters

The workflow was failing when attempting to build and push images with tags
containing characters that aren't allowed in Docker image tags. This was
particularly problematic with Dependabot branch names like
"dependabot/go_modules/github.com/go-jose/go-jose/v3-3.0.4".

This commit adds tag sanitization by replacing invalid characters (slashes
and periods) with hyphens, ensuring all generated Docker image tags comply
with the requirement that repository names only contain the characters
`abcdefghijklmnopqrstuvwxyz0123456789_-./`.

Fixes the error:
"repository can only contain the characters
`abcdefghijklmnopqrstuvwxyz0123456789_-./`"

cf: #1966

Signed-off-by: Chmouel Boudjnah <chmouel@redhat.com>

.github/workflows/container.yaml

@@ -45,7 +45,8 @@ jobs:
           elif [[ ${{ github.ref }} == refs/pull/* ]]; then
             tag=pr-$(echo ${{ github.ref }} | cut -c11-|sed 's,/merge,,')
           else
-            tag=$(echo ${{ github.ref_name }}|sed 's,/merge,,')
+            # Sanitize the tag by replacing invalid characters with hyphens
+            tag=$(echo ${{ github.ref_name }}|sed 's,/merge,,' | sed 's,[/.],-,g')
           fi
           for image in ./cmd/*;do
             ko build -B -t "${tag}" --platform="${{ env.PLATFORMS }}" "${image}"