travis: see if tip is now passing after #44487 fix
travis: see if tip is now passing after #44487 fix

golang/go#44487 was likely causing tip to fail with a panic for the go-fuzz travis tests, perhaps due to the `// +build` in slides/crash.go and elsewhere.

Also update the tested versions of Go.
dvyukov/go-fuzz,dvyukov/go-fuzz