python—用PIP安装了beautifulsoup库，使用的时候老是报错

用PIP安装了beautifulsoup库，使用的时候老是报错
代码如下：

import requests
from bs4 import BeautifulSoup
headers={
'user-agent':' Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.131 Safari/537.36 Edg/92.0.902.67'
    }
res=requests.get('https://www.bilibili.com/',headers=headers)
soup=BeautifulSoup(res.text,'html.parser')
print(soup.prettify())

报错如下：

Traceback (most recent call last):
  File "C:\Users\sun\Desktop\1.py", line 6, in <module>
    res=requests.get('https://www.bilibili.com/',headers=headers)
  File "D:\Python\lib\site-packages\requests\api.py", line 75, in get
    return request('get', url, params=params, **kwargs)
  File "D:\Python\lib\site-packages\requests\api.py", line 61, in request
    return session.request(method=method, url=url, **kwargs)
  File "D:\Python\lib\site-packages\requests\sessions.py", line 528, in request
    prep = self.prepare_request(req)
  File "D:\Python\lib\site-packages\requests\sessions.py", line 456, in prepare_request
    p.prepare(
  File "D:\Python\lib\site-packages\requests\models.py", line 317, in prepare
    self.prepare_headers(headers)
  File "D:\Python\lib\site-packages\requests\models.py", line 451, in prepare_headers
    check_header_validity(header)
  File "D:\Python\lib\site-packages\requests\utils.py", line 978, in check_header_validity
    raise InvalidHeader("Invalid return character or leading space in header: %s" % name)
requests.exceptions.InvalidHeader: Invalid return character or leading space in header: user-agent
>>>

操作系统是win10，IDLE，python3.8.4，已经更新了PIP，并且安装了要使用的第三方库

不能带有空格

img

看错误信息：Invalid return character or leading space in header: user-agent
user-agent 带有空格