Updating Publishing Service to v4.3

[sshushliapin]

Current publishing service image is based on v4.2. This version is not reflected in the image name (e.g. sitecore-ps:9.3.0-windowsservercore-2004).

I'd like to get v4.3 and wondering what's the right way to handle that. Should I just submit a PR upgrading the version in the build.json file? From the other side, there might be a necessity to keep both 4.2 and 4.3 versions. In this case image naming strategy has to be adjusted to include PS version somehow...

Thoughts?

[vtml]

I have a feeling both versions of 4.2 and 4.3 are needed, just like the recent release of JSS v15 for sitecore v10.
#402