dev/sg: make linter timeout more generous
Created by: bobheadxi
I overstimated the speed of our linters in https://github.com/sourcegraph/sourcegraph/pull/36193 - there was a failure on main just now where two checks timed out: https://buildkite.com/sourcegraph/sourcegraph/builds/150604
Test plan
n/a, I looked at the past few runs and they all take just over 3 minutes