您可以使用以下帮助器函数将日期字符串列表规范化为您希望的格式（如果输入日超出范围，请改用月份的结束日）

func getLastDayOfMonth(t time.Time) time.Time {
    lastDayOfMonth := time.Date(t.Year(), t.Month()+1, 1, 0, 0, 0, -1, time.UTC)
    return lastDayOfMonth
}

func formatSlices(dates []string) []string {
    var formattedDates []string
    for _, date := range dates {
        dateSlice := strings.Split(date, "-")
        rawDate, err := time.Parse("2006-01-02", dateSlice[0]+"-"+dateSlice[1]+"-01")
        if err != nil {
            fmt.Println(err)
        }
        lastDayOfMonth := getLastDayOfMonth(rawDate)
        newDate := date
        rawDay, err := strconv.Atoi(dateSlice[2])
        if err != nil {
            fmt.Println(err)
        }
        if lastDayOfMonth.Day() < rawDay {
            newDate = dateSlice[0] + "-" + dateSlice[1] + "-" + strconv.FormatInt(int64(lastDayOfMonth.Day()), 10)
        }
        formattedDates = append(formattedDates, newDate)
    }
    return formattedDates
}

完整代码：https://go.dev/play/p/D_yWY76GyLh