go.mod alias support

[c1982]

Hi @alihanyalcin ;

In some projects, they can change the go.mod file name with the -modfile parameter.

Just like this: -modfile=local.mod

However this line will not be able to capture go.mod.

https://github.com/alihanyalcin/gomup/blob/8539e7460b058e7933de8ddd6e8336bc602ae2aa/gomup.go#L115

Not: I wrote to remember ✋