travis: run --ci-master for non-PR
travis: run --ci-master for non-PR

Closes Homebrew/homebrew#44302.

Signed-off-by: Xu Cheng <9a05244150b861e40c78843b801eed71bca54eac@me.com>

alyssais/brew,hanxue/linuxbrew,bfontaine/brew,maxim-belkin/brew,bfontaine/brew,toonetown/homebrew,muellermartin/dist,staticfloat/brew,Linuxbrew/brew,DomT4/brew,MikeMcQuaid/brew,DomT4/brew,aw1621107/brew,JCount/brew,mahori/brew,palxex/brew,konqui/brew,mahori/brew,ilovezfs/brew,mahori/brew,ilovezfs/brew,vitorgalvao/brew,gordonmcshane/homebrew,rwhogg/brew,aw1621107/brew,zmwangx/brew,gregory-nisbet/brew,mistydemeo/homebrew,gregory-nisbet/brew,Homebrew/brew,jmsundar/brew,Linuxbrew/brew,nandub/brew,DomT4/brew,mistydemeo/homebrew,tonyg/homebrew,toonetown/homebrew,staticfloat/brew,hanxue/linuxbrew,amar-laksh/brew_sudo,muellermartin/dist,alyssais/brew,pseudocody/brew,amar-laksh/brew_sudo,alyssais/brew,reelsense/brew,konqui/brew,konqui/brew,muellermartin/dist,amar-laksh/brew_sudo,staticfloat/brew,pseudocody/brew,bfontaine/brew,reitermarkus/brew,EricFromCanada/brew,vitorgalvao/brew,mgrimes/brew,zmwangx/brew,claui/brew,sjackman/homebrew,ilovezfs/brew,Homebrew/brew,tonyg/homebrew,gregory-nisbet/brew,maxim-belkin/brew,vitorgalvao/brew,mahori/brew,claui/brew,reitermarkus/brew,Homebrew/brew,reelsense/brew,nandub/brew,sjackman/homebrew,reitermarkus/brew,mistydemeo/homebrew,Linuxbrew/brew,gordonmcshane/homebrew,nandub/brew,AnastasiaSulyagina/brew,DomT4/brew,EricFromCanada/brew,rwhogg/brew,MikeMcQuaid/brew,sjackman/homebrew,Homebrew/brew,mgrimes/brew,toonetown/homebrew,reelsense/brew,claui/brew,mgrimes/brew,AnastasiaSulyagina/brew,Linuxbrew/brew,claui/brew,gordonmcshane/homebrew,AnastasiaSulyagina/brew,maxim-belkin/brew,jmsundar/brew,JCount/brew,hanxue/linuxbrew,palxex/brew,rwhogg/brew,EricFromCanada/brew,palxex/brew,MikeMcQuaid/brew,EricFromCanada/brew,aw1621107/brew,tonyg/homebrew,sjackman/homebrew,pseudocody/brew,konqui/brew,zmwangx/brew,MikeMcQuaid/brew,nandub/brew,jmsundar/brew,JCount/brew,vitorgalvao/brew,reitermarkus/brew,JCount/brew