[BUG] Normalize Tag Name with Lowercasing

[bduverger]

Version

redhat-actions/push-to-registry@v2

Describe the bug

The bug was introduce in redhat-actions/push-to-registry@v2.10 with this PR #94 . The problem is this GitHub action lowercase the image tag but it's not in Docker standard. It's really nice to lowercase the image name but I got issue whtn I try later to download the tag with uppercase, because it was push with lowercase. And it
https://docs.docker.com/engine/reference/commandline/tag/#extended-description

Steps to reproduce, workflow links, screenshots

With Docker CLI, if I try to push an image with a name which contains upercase, I got this message:
invalid reference format: repository name must be lowercase
But I can push an image with a tag which contains uppercases, in Docker Hub or Quay.io:

So I think the PR #94 , related to this issue, is too restrive and this GitHub action shouldn't tranform the tag to be lowercase, just the image name if needed.

[bayou-brogrammer]

in the meantime, you can use this workaround

# Workaround bug where capital letters in your GitHub username make it impossible to push to GHCR.
      # https://github.com/macbre/push-to-ghcr/issues/12
      - name: Lowercase Registry
        id: registry_case
        uses: ASzc/change-string-case-action@v6
        with:
          string: ${{ env.IMAGE_REGISTRY }}