Bug: Can not show time.Duration

[soluty]

time.Duration will cause ( missing ',' in argument list ) error
i wrote a hack and it can work well. change method gofumptFormatExpr

func gofumptFormatExpr(w io.Writer, fset *token.FileSet, expr ast.Expr, opt gofumpt.Options) error {
	// First use go/format to convert the expression to Go syntax.
	var tmp bytes.Buffer
	if err := format.Node(&tmp, fset, expr); err != nil {
		return err
	}
	rs := []rune(tmp.String())
	var firstNum int
	for i, v := range rs {
		if v == '(' {
			if rs[i+1] >= '0' && rs[i+1] <= '9' {
				firstNum = i + 1
				break
			}
		}
	}
	if firstNum > 0 {
		rs0 := rs[:firstNum]
		rs1 := rs[firstNum:]
		var hasChar bool
		for _, v := range rs1 {
			if v < '0' || v > '9' {
				hasChar = true
				break
			}
		}
		if hasChar {
			rs1 = append([]rune{'_'}, rs1...)
		}
		rs = append(rs0, rs1...)
	}
	tmpString := string(formatCompositeLiterals(rs))

[slimsag]

Thanks for filing this, and sorry for the delayed follow-up. I think it would make sense to add support for time.Duration and time.Time natively. Happy to accept a PR for this if anyone has time and can add a few test cases alongside it.