Auto merge of #7541 - alexcrichton:try-apt-update, r=alexcrichton
Auto merge of #7541 - alexcrichton:try-apt-update, r=alexcrichton

Run `apt update` before `apt install`

Trying to fix recent errors on CI...

vojtechkral/cargo,tsurai/cargo,vojtechkral/cargo,tsurai/cargo,tsurai/cargo,eminence/cargo,tsurai/cargo,nipunn1313/cargo,rust-lang/cargo,vojtechkral/cargo,nipunn1313/cargo,tshepang/cargo,rustyhorde/cargo,rust-lang/cargo,nipunn1313/cargo,vojtechkral/cargo,rustyhorde/cargo,tshepang/cargo,tshepang/cargo,eminence/cargo,tsurai/cargo,eminence/cargo,rust-lang/cargo,rustyhorde/cargo,tshepang/cargo,eminence/cargo,rustyhorde/cargo,nipunn1313/cargo,rust-lang/cargo