String configs that look like numbers can get corrupted on parse

[tsholmes]

Sample case:

package main

import (
	"fmt"

	"github.com/segmentio/conf"
)

func main() {
	var config struct {
		StringValue string `conf:"string-value"`
	}

	conf.LoadWith(&config, conf.Loader{
		Args: []string{"-string-value", "0123456789"},
	})

	fmt.Println(config.StringValue)
}

Outputs:

1.23456789e+08

[nickatsegment]

Fixed by 312d8ed?w=1 probably