feat(rubygems): support GitHub Packages (#11107)

lib/datasource/rubygems/__fixtures__/dependencies-rails.dat

lib/datasource/rubygems/__snapshots__/index.spec.ts.snap

lib/datasource/rubygems/common.ts

lib/datasource/rubygems/get-rubygems-org.ts

lib/datasource/rubygems/get.ts

lib/datasource/rubygems/index.spec.ts

lib/datasource/rubygems/releases.ts

lib/datasource/rubygems/types.ts

lib/types/marshal.d.ts

lib/util/http/index.ts

lib/util/http/types.ts

package.json

test/util.ts

yarn.lock