Newer go version required to compile bettercap

[Faelian]

On the website, in Compiling from Sources it is indicated than version above 1.8 of go is required.

But following these instructions with go 1.11, the build will fail.

$ go version                           
go version go1.11.6 linux/amd64

$ go get github.com/bettercap/bettercap
package crypto/ed25519: unrecognized import path "crypto/ed25519" (import path does not begin with hostname)