Bump rules_go to 0.18.5 and go tool chain to 1.12.5.
Bump rules_go to 0.18.5 and go tool chain to 1.12.5.

PiperOrigin-RevId: 248719758
Change-Id: I0a87d8befd56c5a791585818e9b84ac0c443b0df

google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor,google/gvisor