ci: new image build workflow

[emerconn]

closes https://github.com/akpw/mktxp/issues/185

• add semver tags to the images, matching the semver tags in git
• migrate off the workflow template, which had deprecated commands and NodeJS versions

[MarcWort]

Looks good at first glance. Good work :tada:

[MarcWort]

Nice. @akpw Could you push a tag to trigger the build of a new image with the correct versioning scheme?

[akpw]

OK done