Have Tails::Download::HTTPS require TLS 1.2+
_Originally created by @intrigeri on [#11815 (Redmine)](https://public-redmine-archive.tails.boum.org/code/issues/11815)_
We currently set `CURLOPT_SSLVERSION, CURL_SSLVERSION_TLSv1`. In Jessie,
`CURL_SSLVERSION_TLSv1_2` should be supported, and the websites we use
this class for (i.e. our own one) support TLS 1.2. This will affect
Tails Upgrader and (once tails/tails#11810 is done) `tails-security-check`. The
diff is trivial, we simply need to test that it actually works, and
build a new `tails-perl5lib` package.
Feature Branch: perl5lib:feature/11815-tls-1.2
### Related issues
- **Related to** tails/sysadmin#14588
issue