Add tags with major and minor version number

[devopsix]

I would like to be able to pin the exact version, e.g. 53.3. Without being able to pin an exact version, my build would break if say 53.4 would contain a bug that affects me.

For an example, check out the tagging scheme used for PostgreSQL images: https://github.com/docker-library/docs/tree/master/postgres#supported-tags-and-respective-dockerfile-links