Switch templates and packages to Debian Buster

[eloquence]

We want to switch all Debian-based VM templates and workstation packages to Debian Buster, without the complexity of supporting two Debian releases at the same time. This breaks down as follows:

Completed

• Attempt to run securedrop-client on Debian Buster - Verify basic client operations in Debian Buster VM, including Qubes-specific operations securedrop-client#528
• Test version of securedrop-workstation template with Buster and grsec - update SQLAlchemy to 1.3.0 to mitigate CVE-2019-7548 and CVE-2019-7164 securedrop-client#308
• Update FPF's PyPI index - Adds wheels for client and proxy in Python3.7 securedrop-builder#86
• Update build requirements for Buster packages - Updates the script to add multiple wheel hashes securedrop-builder#85
• Add support for securedrop-export Debian Buster tests - Add Buster test job to CI securedrop-export#24

11/20-12/4 sprint

• Make updates to package build logic for client/proxy/export builds - Update package build logic to support securedrop-client builds on Buster securedrop-builder#88, Update package build logic to support securedrop-proxy builds on Buster securedrop-builder#91, Update package build logic to support securedrop-export builds on Buster securedrop-builder#92
• Add Buster builds to CI - Switch CI jobs to Debian Buster/Python 3.7 securedrop-client#527, [securedrop-proxy] Add Buster build job securedrop-proxy#143, Add Buster build job securedrop-export#30
• Start creating nightly Buster builds - Build and commit buster packages for securedrop-workstation builds securedrop-builder#76
• Upload Buster-based RPM - remove unused sdc_home securedrop-client#344
• Switch securedrop-workstation template to Buster remove unnecessary conversations cache securedrop-client#345

12/5-12/18 sprint

• Switch to Whonix 15 (which is also Stretch->Buster) - Add "Delete" button to Selected Source item in Source List securedrop-client#300

[eloquence]

Updated epic per discussions at sprint planning today. Need a bit more discussion/scoping around the goals for updating the package build logic (e.g., is it acceptable to break stretch builds, and if so, when will we cross that line?).

[eloquence]

(Keeping epic on the backlog, but we should be able to fully close this out in the 11/20-12/4 sprint.)

[eloquence]

Closing as all tasks in epic were completed and make all should now result in a Buster-based SDW; feel free to reopen if there are follow-up tasks that should be tracked in this epic. :)

[conorsch]

freedomofpress/securedrop-client#300 still outstanding, but we're in the home stretch! 😃