Regular expression search for context, configurable sort for climb and prune

What's Changed

• Sync the .packit.yaml config to downstream repo by @psss in #269
• Set up default owners and the pull request checklist by @psss in #270
• Implement regular expression search for context by @psss in #272
• Make sorting in climb() and prune() configurable by @psss in #271
• Release fmf-1.6.0 by @psss in #273

Full Changelog: 1.5.0...1.6.0