build: update revert pattern in changelog generator
build: update revert pattern in changelog generator

This change will handle github reverts such as https://github.com/angular/angular-cli/pull/19736

ocombe/angular-cli,clydin/angular-cli,clydin/angular-cli,clydin/angular-cli,Brocco/angular-cli,Brocco/angular-cli,angular/angular-cli,geofffilippi/angular-cli,ocombe/angular-cli,angular/angular-cli,geofffilippi/angular-cli,ocombe/angular-cli,Brocco/angular-cli,catull/angular-cli,catull/angular-cli,ocombe/angular-cli,catull/angular-cli,clydin/angular-cli,Brocco/angular-cli,catull/angular-cli,geofffilippi/angular-cli,ocombe/angular-cli,Brocco/angular-cli,angular/angular-cli,geofffilippi/angular-cli,angular/angular-cli