fix: use correct type in GitDataClient::updateReference body#256

ckolek-figs wants to merge 1 commit intospotify:masterspotify/github-java-client:masterfrom

ckolek-figs:bugfix/git-data-client-update-ref-forceckolek-figs/github-java-client:bugfix/git-data-client-update-ref-forceCopy head branch name to clipboard