Fix tags for release image by using manifest push

[fwilhe]

The image of version 0.3 does not properly contain the multi-arch image as expected. It looks like 'manifest push' is the command we should use rather than 'image push'.

Note: As of today, github actions has podman v 3.x

The cli has changed in those versions, see:

• docs for v3 https://docs.podman.io/en/v3.0/markdown/podman-manifest-push.1.html
• docs for current https://docs.podman.io/en/stable/markdown/podman-manifest-push.1.html