Validate if gem push succeeded
Validate if gem push succeeded

I've now "published" the gem twice (but not to RubyGems.org) because the
`gem push` command failed. Validate that it actually succeeded and only
then continue the process.

appsignal/appsignal-ruby,appsignal/appsignal-ruby,appsignal/appsignal-ruby,appsignal/appsignal-ruby