FTR:
Package python-requests automatically looks at certificate bundle from
ca-certificates package.  However, in case you have pip'installed
python requests, note that it does not use ca-certificates bundle - and you
can possibly use the REQUESTS_CA_BUNDLE environment variable.

I would be more interested in a copr configuration option with which I could pass the required certificate.

Also, the actual report in case of missing certificate is:

===
$ copr-cli --config ~/.config/rhcopr list
Something went wrong:
Error: Connection error GET https://copr.devel.redhat.com/api/coprs/praiskup/
===

There could be better error report saying that HTTPS is the issue, reported
by Jakub.

(In reply to Miroslav Vadkerti from comment #2)
> I would be more interested in a copr configuration option with which I could
> pass the required certificate.

Fixing the $Summary accordingly.  Config option makes sense, as a complement
command line option makes sense too.

Also idea to consider:  What about to add the CA into configuration file
in-line?  (inspired by openvpn <ca></ca>)