Auto merge of #6020 - dwijnand:stale-bot, r=alexcrichton
Auto merge of #6020 - dwijnand:stale-bot, r=alexcrichton

Setup Stale Probot

r?  @alexcrichton
/cc @Eh2406

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