Release SecureDrop Workstation 0.5.7

[conorsch]

We've got a single change we want to ship in a new rpm version, that of migrating the Fedora templates ahead of the current EOL window (#735). Tracking the usual steps related to a release here:

• Review and merge Fedora template changes - Update Fedora version to 34 #736
• Bump RPM version to 0.5.7 - Update Fedora version to 34 #736
• Create signed tag for 0.5.7 - https://github.com/freedomofpress/securedrop-workstation/releases/tag/0.5.7
• Build RPM, sign with test key, submit to dev lfs repo (this is necessary to keep staging in sync even if we don't test separately) - Add sdw-dom0-config 0.5.7 RPM securedrop-yum-test#29
• Resign RPM with prod key, submit to prod lfs repo - Release SecureDrop Workstation 0.5.7 #737
• Handle pilot comms

Given the extensive testing we've done, I'm fine with submitting PRs to both locations and merging simultaneously. @creviera let me know if you disagree!

[conorsch]

Working on this today.

[conorsch]

Prod RPM is up and ready for review. Today's Friday, so let's wait till early next week to merge and thereby release.

[eloquence]

This was completed via freedomofpress/securedrop-yum-prod#24.