go run github.com/FiloSottile/mkcert no longer works outside with Go 1.14

[eliasnaur]

The fix for golang/go#32027 disallows go run and friends outside a module (when GO111MODULE=on):

$ GO111MODULE=on go run github.com/FiloSottile/mkcert
cannot find module providing package github.com/FiloSottile/mkcert: working directory is not part of a module

[FiloSottile]

Sigh, it was too good for this world.