[ci skip] move linting into before_script stage
[ci skip] move linting into before_script stage

If lint is in before_script, it will fail before running tests, which
is less confusing

jordanyaker/polymer,ikeagold/polymer,gronke/polymer,MartinsThiago/polymer,gazal-k/polymer,mgiuffrida/polymer,ktiedt/polymer,yforrest/polymer,JeremybellEU/polymer,yforrest/polymer,gronke/polymer,yforrest/polymer,Polymer/polymer,gazal-k/polymer,jordanyaker/polymer,MartinsThiago/polymer,JeremybellEU/polymer,JeremybellEU/polymer,gazal-k/polymer,ikeagold/polymer,Polymer/polymer,gronke/polymer,mgiuffrida/polymer,jordanyaker/polymer,ikeagold/polymer,mgiuffrida/polymer,ktiedt/polymer,MartinsThiago/polymer,ktiedt/polymer,Polymer/polymer