python图片链接正则表达式

问题遇到的现象和发生背景

正则表达式无法正确提取到网站地址

import requests
import re
import os
if __name__ == '__main__':
    if not os.path.exists('./nbaLibs'):
        os.mkdir('./nbaLibs')
    url='https://tieba.baidu.com/f?kw=nba'
    headers = {
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/107.0.0.0 Safari/537.36 Edg/107.0.1418.42'
    }
    page_text=requests.get(url=url,headers=headers).text
    ex='
'
    #ex ='(?:https?:\/\/)?[a-zA-Z0-9][-a-zA-Z0-9]{0,62}(?:\.[a-zA-Z0-9][-a-zA-Z0-9]{0,62})+.+\.(gif|png|jpg|jpeg|webp|svg|psd|bmp|tif)'
    img_src_list = re.findall(ex, page_text, re.S)
    print(img_src_list)
#
"media_bigpic_wrap">
# "j_retract" id="big_img_1668586480803" src="https://tiebapic.baidu.com/forum/pic/item/0cd7912397dda14415392970f7b7d0a20df486c4.jpg?tbpicau=2022-11-18-05_6b253562deaa086f40d12262ff9c2b7d" onerror="this.src='//tb2.bdstatic.com/tb/static-frs/img/v2/picerr.gif';this.width=82;this.height=75;" style="visibility: visible;">

#图片链接地址：https://tiebapic.baidu.com/forum/pic/item/0cd7912397dda14415392970f7b7d0a20df486c4.jpg?tbpicau=2022-11-18-05_6b253562deaa086f40d12262ff9c2b7d
    for src in img_src_list:
        img_data=requests.get(url=src,headers=headers).content
        image_name=src.split('/')[-1]
        imaPath='./nbaLibs'/+ image_name
        with open(imaPath,'wb') as fp:
            fp.write(img_data)
            print(image_name,'下载成功！！！！')
用代码块功能插入代码，请勿粘贴截图
运行结果及报错内容

无法提取到网址
只显示出一个空列表