Py-droplets

What's Changed
* Added workflow for automatic pypi release by david-zwicker in https://github.com/zwicker-group/py-droplets/pull/14
* Add methods to merge droplets by david-zwicker in https://github.com/zwicker-group/py-droplets/pull/15


**Full Changelog**: https://github.com/zwicker-group/py-droplets/compare/v0.11.0...v0.12.0

What's Changed
* Improved compatibility with `py-pde` david-zwicker
* Expanded length scale detection by david-zwicker in https://github.com/zwicker-group/py-droplets/pull/13

**Full Changelog**: https://github.com/zwicker-group/py-droplets/compare/v0.10.0...v0.11.0

What's Changed
* Added new method for determining length scales by david-zwicker in https://github.com/zwicker-group/py-droplets/pull/11


**Full Changelog**: https://github.com/zwicker-group/py-droplets/compare/v0.9.0...v0.10.0

What's Changed

* Bumped py-pde minimal version to 0.18.0
* Switch to using `transform` method of new grid classes of `py-pde`

**Full Changelog**: https://github.com/zwicker-group/py-droplets/compare/v0.8.1...v0.9.0