bug#36199: Newsboat: HTTPS urls broken

[Robert Smith]

Version information: (from `newsboat --version`)

newsboat 2.13.0
System: Linux 5.1.7-gnu (x86_64)
Compiler: g++ 5.5.0
ncurses: ncurses 6.1.20180127 (compiled with 6.1)
libcurl: libcurl/7.65.0 GnuTLS/3.6.5 zlib/1.2.11 libidn2/2.0.5 
nghttp2/1.35.1 (compiled with 7.63.0)
SQLite: 3.26.0 (compiled with 3.24.0)
libxml2: compiled with 2.9.8

Currently only http feeds are successfully being resolved, all https
feeds fail the SSL verification. I am using the Guix System, and no
other program (web browsers, etc.) exibits this behavior.

An example of the specific error given:
"Error while retrieving https://xkcd.com/rss.xml: SSL peer certificate 
or SSH remote key was not OK"