Common docker image tag for all architectures

[iFergal]

For example, right now we have 1.2.0-dev11 for x86/x64 but 1.2.0-dev11-arm64 for arm.

It would be better if we can have the same tag name for all architectures. I believe a multi-platform docker manifest would work, haven't had time to look into it yet.

The reason it's better is so we can have one compose file for developers on multiple architectures, and in the case of KERIA, if we wanted to build that image on top of the keripy image we would need one tag.

[iFergal]

#832 fixed this