Update ruby and build env

[joemsak]

• Update to ruby 2.7.8 (2.5 just would not cooperate on my host machine)
• Install chromium (the chrome amd64.deb download was no bueno on an M3 mac)
• Update the bundler version (compatible with ruby 2.7)
• Add a github actions workflow for running the tests
• Remove Circle CI config
• Pin down a version of google-protobuf that is supported (missing Google::Protobuf::DescriptorPool#build method in future versions)
  • Subsequently pins down grpc to latest which can use google-protobuf 3.13.x

TODO: is there a way to remove circle CI from the checks?