Bump Go version in check_website to 1.19.3.
Bump Go version in check_website to 1.19.3.

This is to match https://github.com/elves/up/commit/c67704a8c0db0bbd671eccc3a4e3feb8600f4fff.

elves/elvish,elves/elvish,elves/elvish,elves/elvish,elves/elvish