Wordpress plugins are hosted in a Subversion repository, and there’s no way to change that. Personally, I don’t like SVN (though it has it uses), and I prefer to use git over it.
Recently, I had to develop a small Wordpress plugin (which is called Comment Reply Email Notification), and I decided to host it on Github. To publish it to Wordpress, I wrote a small script that copies the plugin files from the git repository to the SVN repository, creates a release tag and effectively releases a new version of the plugin in Wordpress’ official plugin platform.
To use this script, replace the SVN and git repository URLs, and make sure you have an up-to-date VERSION file (preferably using Semantic Versioning rules).