Bump .ruby-version from 2.3.6 to 2.3.7
Bump .ruby-version from 2.3.6 to 2.3.7

axilleas/gitlabhq,axilleas/gitlabhq,jirutka/gitlabhq,mmkassem/gitlabhq,jirutka/gitlabhq,dreampet/gitlab,stoplightio/gitlabhq,axilleas/gitlabhq,dreampet/gitlab,mmkassem/gitlabhq,iiet/iiet-git,axilleas/gitlabhq,iiet/iiet-git,dreampet/gitlab,dreampet/gitlab,iiet/iiet-git,stoplightio/gitlabhq,stoplightio/gitlabhq,mmkassem/gitlabhq,stoplightio/gitlabhq,jirutka/gitlabhq,mmkassem/gitlabhq,iiet/iiet-git,jirutka/gitlabhq