Proposal: gimme module to get the Go version defined in go.mod

[brackendawson]

Since the go directive in a module's go.mod file is a statement of the minimum Go version required to compile the packages in the module, it would be prudent to test that version of Go to ensure that nobody unknowingly introduces a language feature from a newer Go version.

Right now to do this you must list that Go version in your .travis.yml and keep it in sync with the version in your go.mod, which I think is error-prone.

I think it would be useful if there was a new alias to refer to the go directive in the go.mod file, such as:

go:
- stable
- module

It would choose the most recent patch release from that Go version.

[carmanchris31]

In the meantime I put together a zsh hook that mimics fnm's --use-on-cd, extracting the wanted go version based on go.mod and automatically updating using gimme:
https://gist.github.com/carmanchris31/133a9ba4699bf068e6170c59b8d6f281