This is the go_router equivalent of #184119, and will be a follow-up to #182064; we've let several of our packages get quite far behind on analyzer compatibility, and we should catch all the way up to the recently released 12. As always, we should support as large a range as we can easily support, so the lower bound should only increase if necessary to increase the upper bound.

In addition to general ecosystem compat, we should do this soon to avoid future issues like flutter/packages#11358 where we can't update Pigeon because go_router_builder is too far behind.