Pipen-args

- ⬆️ Drop support to python 3.7
- ⬆️ Bump pipen to 0.9
- ⬆️ Bump pipen-annotate to 0.7.1
- ♻️ Register the plugin by default, no need to import
- 👷 Remove python 3.7 from CI

**Full Changelog**: https://github.com/pwwang/pipen-args/compare/0.8.0...0.9.0

- ⬆️ Upgrade pipen-annotate to 0.6

**Full Changelog**: https://github.com/pwwang/pipen-args/compare/0.7.4...0.8.0

- 💥 Change metadata key hide to hidden and remove atype
- ⬆️ Update pipen-annotate to 0.5.2

**Full Changelog**: https://github.com/pwwang/pipen-args/compare/0.7.3...0.7.4

- ⬆️ Adopt argx 0.2.6

**Full Changelog**: https://github.com/pwwang/pipen-args/compare/0.7.2...0.7.3

- 🐛 Remove debug print statement from ProcGroup constructor
- 🔍 Update test for attribute hide

**Full Changelog**: https://github.com/pwwang/pipen-args/compare/0.7.1...0.7.2

- 🔧 Fix opts not passed to procgroup not taking effect

**Full Changelog**: https://github.com/pwwang/pipen-args/compare/0.7.0...0.7.1