Update required_ruby_version in gemspec
Update required_ruby_version in gemspec

This project only supports Ruby 2.0.0 and later.

Support for 1.9.3 was removed in ed1e2264147fc9ede9a38f4546ec49c7d33bdf74.

gds-operations/vcloud-launcher,gds-operations/vcloud-launcher,gds-operations/vcloud-launcher