the release tag CI is run when semantic versioned tags are pushed.
it is presumed that the commit and/or PR to the release branch being
tagged has already passed the lints.
this gets around Github Actions CI running check-proto-breaking-remote
which compares the pushed commit against _master_ (not the previous release)
* build & publish rocksdb docker images merge to master
* publish docker images on push of release version tags
NOTE: New docker image tag pattern. ALL tags now include database suffix
ex. <githash>-goleveldb, v0.25.0-alpha.1-rocksdb, master-rocksdb, etc
* update dockerfiles for better caching
* update all github action workflow versions
* improve caching of go packages
* cache docker image layers for reuse between runs
* update dockerignore to remove non-essential files
