For Debian 10 Buster
Confirm version of curl frozen

Check to see if there is a newer version of tls supported in curl manpage
https://curl.haxx.se/docs/manpage.html

If so:

grep Whonix code for --tlsv1.2
https://github.com/Whonix

update
https://www.whonix.org/wiki/Template:Curl_Secure

Duplicate/Re-tag/Close&Create ticket for next Debian version.