cmd/go: mod list type Module is missing toolchain version

[egonk7615]

See https://github.com/golang/go/blob/master/src/cmd/go/internal/list/list.go

    type Module struct {
        Path       string        // module path
        Query      string        // version query corresponding to this version
        Version    string        // module version
        Versions   []string      // available module versions
        Replace    *Module       // replaced by this module
        Time       *time.Time    // time version was created
        Update     *Module       // available update (with -u)
        Main       bool          // is this the main module?
        Indirect   bool          // module is only indirectly needed by main module
        Dir        string        // directory holding local copy of files, if any
        GoMod      string        // path to go.mod file describing module, if any
        GoVersion  string        // go version used in module
        Retracted  []string      // retraction information, if any (with -retracted or -u)
        Deprecated string        // deprecation message, if any (with -u)
        Error      *ModuleError  // error loading module
        Sum        string        // checksum for path, version (as in go.sum)
        GoModSum   string        // checksum for go.mod (as in go.sum)
        Origin     any           // provenance of module
        Reuse      bool          // reuse of old module info is safe
    }

    type ModuleError struct {
        Err string // the error itself
    }

We have GoVersion string // go version used in module, which contains go X.Y.Z directive.

It would be nice to have something like GoToolchain string too which would contain toolchain goX.Y.Z directive.