Ruby 2.7 warnings during build-time due to package_cloud gem

There is a warning being thrown from json_pure version 1.8.1 a bunch of times:

./builds/gitlab-org/build/omnibus-gitlab-mirror/gems/ruby/2.7.0/gems/json_pure-1.8.1/lib/json/common.rb:155: warning: Using the last argument as keyword parameters is deprecated

It seems this is a very old version of json_pure, and is locked by package_cloud dependency. I've opened an upstream issue to see if they have any intention of improving this or not: https://github.com/computology/packagecloud-ruby/issues/29