Release v3.21.0

This release adds enhancements, bug fixes and test improvements.

Enhancements:

• Documentation and output improvements for new verify alias
• zsh shell command completion
• Prevent swupd from running interactive commands
• Require force flag to prevent users to rely on unsafe http connections
• Create a config file to set default flags to be used with swupd commands
• Supporting new Manifest feature: also-add (optional) bundles.
• Rework on preventing flag duplication
• Don't print progress report on autoupdate

Bug fixes:

• Root required in cases where it shouldn't
• Download progress bug could print percentages larger than 100%
• When using a local mirror, continue update even if not possible to check if mirror is outdated

Tests:

• Including extra signature verification tests, like key rotation and chained certificate checks
• Fixing some incorrect and broken tests
• Extra tests added