CircleCI config: use "browsers" image (#8051)
CircleCI config: use "browsers" image (#8051)

Change the CircleCI image to one that has Chrome to fix failing nightly e2e tests
HuddledMasses/Prebid.js,PubWise/Prebid.js,ImproveDigital/Prebid.js,PubWise/Prebid.js,ImproveDigital/Prebid.js,prebid/Prebid.js,prebid/Prebid.js,gumgum/Prebid.js,HuddledMasses/Prebid.js,HuddledMasses/Prebid.js,gumgum/Prebid.js,PubWise/Prebid.js,prebid/Prebid.js,gumgum/Prebid.js,ImproveDigital/Prebid.js