Update GlobaLeaks APT source URL to HTTPS

[orazioedoardo]

Packages are obviously signed but HTTPS protects users from potential MITM attacks exploiting bugs like this https://justi.cz/security/2019/01/22/apt-rce.html

Before submitting a pull request, please ensure the following:

• The pull request includes a description of the problem you're trying to solve.
• The pull request provides an overview of the suggested solution.
• The proposed code is fully functional.
• The proposed code includes relevant tests to verify its functionality.
• All new and existing tests pass successfully.
• Overall code quality and test coverage metrics are not reduced by more than 0.5%

[evilaliv3]

Very proper and correct feedback @orazioedoardo

We very look forward to good contributions like your.

I confirm that regardless the fact the attack would cause a downgrade mostly its impact could be significant.

I will definitely ensure to retest your patch and take it to production.

Thank you!

we welcome you on our community.globaleaks.org (out of slack in matter of days!)