Workalendar

- Added Israel holidays eves and removed holidays which are not affecting the working days in Israel (461).
- Fix warning in China's holidays to dynamically read supported years, thx fredrike (459).

- Fix several miscalculations in Georgia (USA) calendar (451).

- Fix Family Day for British Columbia (Canada) which was switched from 2nd to 3rd Monday of February in 2019 - thx jbroudou for the bug report (454).

- **BREAKING CHANGE** Drop Support for Python 2 - EOL January 1st 2020 (442).
- Added Ukraine calendar, by apelloni.
- Small cleanup in the ``.travis.yml`` file, thx to Natim.

ISO Registry API Change

- Changes in the ``registry.items()`` method API.
- This method is aliased to ``get_calendars()``. In a near release, the ``items()`` method will change its purpose.
- The ``get_calendars()`` method accepts an empty/missing ``region_codes`` argument to retrieve the full registry. Please see the [ISO Registry documentation](https://workalendar.github.io/workalendar/iso-registry.html) for extensive usage docs (#403, 375).

New calendars

- Added Serbia calendar, by apelloni (435).
- Added Argentina calendar, by ftatarli (419).

Other changes

- Update China's public holidays for 2020, thx nut-free (429).
- Update Malaysia and Singapore for 2021 (Deepavali + Thaipusam) by jack-pace (432).
- Small refactorings on the Gevena (Switzerland) holiday class, thx to cw-intellineers (420).

- **Bugfix** for USA: Fixed incorrect implementation for Thanksgiving Friday, thx deveshvar (422).
- Fix Advanced usage documentation about Thanksgiving Day (426).
- Added Geneva calendar by cw-intellineers (420).