request: publish a new release

[lisac...@gmail.com]

Would it be possible to cut a new release? I'd like to use the WSDLRequest headers feature introduced in PR#753 (post-v2.11.2) and am under the impression that I can't point to an unreleased version (with github url & SHA) in a gem's gemspec. Thanks.

(PR#753: https://github.com/savonrb/savon/pull/753)