Support Go 1.19

[andig]

Homebrew/homebrew-core#107165 fails due to

panic: Something in this program imports go4.org/unsafe/assume-no-moving-gc to declare that it assumes a non-moving garbage collector, but your version of go4.org/unsafe/assume-no-moving-gc hasn't been updated to assert that it's safe against the go1.19 runtime. If you want to risk it, run with environment variable ASSUME_NO_MOVING_GC_UNSAFE_RISK_IT_WITH=go1.19 set. Notably, if go1.19 adds a moving garbage collector, this program is unsafe to use.

This can be fixed by upgrading go4.org/unsafe/assume-no-moving-gc according to quic-go/quic-go#3491

[rfratto]

Thanks, #1985 should take care of this. Will this block updating the Go formula to 1.19? We typically release a new version of Grafana Agent every six weeks, but we can figure something out if this is needed urgently.