import time, datetime, pytz
time_n = "2020-05-14 15:15:38"
time_format = time.strptime(time_n, "%Y-%m-%d %H:%M:%S")
timestamp = int(time.mktime(time_format))

def local_to_utc(local_ts, utc_format='%Y-%m-%dT%H:%MZ'):
    local_tz = pytz.timezone('Asia/Shanghai')    #定義本地時區
    local_format = "%Y-%m-%d %H:%M:%S"               #定義本地時間format

    time_str = time.strftime(local_format, time.localtime(local_ts))    #首先將本地時間戳轉化為時間元組，用strftime格式化成字串
    dt = datetime.datetime.strptime(time_str, local_format)             #將字串用strptime 轉為為datetime中 datetime格式
    local_dt = local_tz.localize(dt, is_dst=None)                       #給時間新增時區，等價於 dt.replace(tzinfo=pytz.timezone('Asia/Chongqing'))
    utc_dt = local_dt.astimezone(pytz.utc)                              #astimezone切換時區
    return utc_dt.strftime(utc_format)

print(local_to_utc(timestamp))  # 2020-05-14T07:15Z