[BUG] podman login fails when missing docker configs

[nzwulfin]

Version

redhat-actions/push-to-registry@v2

Describe the bug

When using a buildah or podman image without docker, the plugin fails writing a non-existent and unneeded credentials file even though the login was successful.

Steps to reproduce, workflow links, screenshots

Exporting REGISTRY_AUTH_FILE=/run/containers/0/auth.json
✍️ Writing registry credentials to "/root/.docker/config.json"
::error::Error: ENOENT: no such file or directory, open '/root/.docker/config.json'

There is a workaround from where this behavior was introduced in closing #18 but it doesn't make sense to me that I need to have a custom buildah image to support a tool that isn't installed or part of the workflow.

Podman doesn't use the docker config files, so if this is an attempt to support docker login in addition to podman login, then this should be probably be looked at again to not cause failures where not required. At the very least it shouldn't error the entire action.