yt-dl.org expired intermediate cert, causes youtube-dl -U fail

[broberts01]

Checklist

• I'm reporting a broken site support issue
• [x ] I've verified that I'm running youtube-dl version 2020.06.16.1
• I've checked that all provided URLs are alive and playable in a browser
• I've checked that all URLs and arguments with special characters are properly quoted or escaped
• [x ] I've searched the bugtracker for similar bug reports including closed ones
• I've read bugs section in FAQ

Verbose log

$ youtube-dl -U -v
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'-U', u'-v']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2020.06.16.1
[debug] Python version 2.7.5 (CPython) - Linux-3.10.0-957.1.3.el7.x86_64-x86_64-with-centos-7.7.1908-Core
[debug] exe versions: ffmpeg 3.4.1-static, ffprobe 3.4.1-static
[debug] Proxy map: {}
Traceback (most recent call last):
  File "/usr/local/bin/youtube-dl/youtube_dl/update.py", line 46, in update_self
    newversion = opener.open(VERSION_URL).read().decode('utf-8').strip()
  File "/usr/lib64/python2.7/urllib2.py", line 431, in open
    response = self._open(req, data)
  File "/usr/lib64/python2.7/urllib2.py", line 449, in _open
    '_open', req)
  File "/usr/lib64/python2.7/urllib2.py", line 409, in _call_chain
    result = func(*args)
  File "/usr/local/bin/youtube-dl/youtube_dl/utils.py", line 2736, in https_open
    req, **kwargs)
  File "/usr/lib64/python2.7/urllib2.py", line 1214, in do_open
    raise URLError(err)
URLError: <urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:618)>

ERROR: can't find the current version. Please try again later.```


## Description

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Wish I could re-open a "could not repro" ticket because it most certainly is reproducible (#25541). This is not a code issue per se, but rather a yt-dl.org SSL config issue which causes the update to not function.
$ youtube-dl --version
2020.06.16.1

$ youtube-dl -U
ERROR: can't find the current version. Please try again later.

We've seen this issue with a number of sites which are accessed via command line tools such as PHP or Python.  Fixing the intermediate.crt has resolved the issue.  The section of interest from SSLlabs:
<img width="1105" alt="Screen Shot 2020-06-16 at 12 59 59 PM" src="https://user-images.githubusercontent.com/6480339/84823089-9ff75180-afd2-11ea-821f-4e147ed38037.png">