workflows/build-ci-container: Fix container push

After the changes in 89001d1, the
container pushes failed, because it was attempting to push the same
container twice.  This fixes the sed expression used to push the :latest
alias for each container.

Author: tstellar

.github/workflows/build-ci-container.yml

@@ -96,7 +96,7 @@ jobs:
         run: |
           function push_container {
             image_name=$1
-            latest_name=$(echo $image_name | sed 's/:[.0-9]\+$/:latest/g')
+            latest_name=$(echo $image_name | sed 's/:[a-f0-9]\+$/:latest/g')
             podman tag $image_name $latest_name
             echo "Pushing $image_name ..."
             podman push $image_name