Fix cert verify failed

[Arnie97]

This patch exploits the root CA certificates provided by the certifi package (if it is present in the system).

This fixs an error like the following when calling repomd on macOS or inside minimal Docker images:

<urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:1056)>

[carlwgeorge]

I don't have a mac. What are the steps to reproduce this error inside a minimal container image?

[carlwgeorge]

I took a guess at the steps. This works for me, no errors.

[carl@teal:~]$ podman run -it --rm python:3.10 bash
root@ef4eea6c11c3:/# pip install repomd
Collecting repomd
  Downloading repomd-0.2.1-py3-none-any.whl (3.9 kB)
Collecting lxml
  Downloading lxml-4.8.0-cp310-cp310-manylinux_2_17_x86_64.manylinux2014_x86_64.manylinux_2_24_x86_64.whl (7.0 MB)
     ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 7.0/7.0 MB 41.1 MB/s eta 0:00:00
Collecting defusedxml
  Downloading defusedxml-0.7.1-py2.py3-none-any.whl (25 kB)
Installing collected packages: lxml, defusedxml, repomd
Successfully installed defusedxml-0.7.1 lxml-4.8.0 repomd-0.2.1
WARNING: Running pip as the 'root' user can result in broken permissions and conflicting behaviour with the system package manager. It is recommended to use a virtual environment instead: https://pip.pypa.io/warnings/venv
root@ef4eea6c11c3:/# python
Python 3.10.4 (main, Apr 20 2022, 18:21:23) [GCC 10.2.1 20210110] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import repomd
>>> repo = repomd.load('https://dl.fedoraproject.org/pub/epel/9/Everything/x86_64/')
>>> repo.find('htop')
<Package: "htop-3.1.2-3.el9.x86_64">