Update psyplot min version

See merge request !54

[release] compatibility fixes and code formatting

See merge request !53

update skeleton

See merge request !52

fix DISPLAY issues in CI

See merge request !51

add ci matrix

See merge request !50

Fix map extent

See merge request !49

Add google map detail

See merge request !48

migrate to psyplot-plugin-template

See merge request !47

Merge pull request #45 from psyplot/develop

* add target_extent for mapdensity

closes #43

* typo

* add test for density with lonlatbox

see #43

* update changelog

* use psyplot-ci-orb@1.5.32

Fix projection issues

Fixed
-----

- `false_easting` and `false_northing` are now expected to be optional
  arguments for most projections (see #41)

Changed
-------
- we now use the `convert_coordinate` method that has been introduced
  in psyplot/psyplot#39 and psyplot/psy-simple#30. See #41

* make false_easting and false_northing optional

* add tests for false_easting and false_northing

* use the convert_coordinate method to transform plots

* update CHANGELOG

As with psyplot 1.4.0, psy-maps is now continuously tested and deployed with CircleCI.

Fixed
-----

-   psy-maps is now officially licensed under LGPL-3.0-only, see [#36](https://github.com/psyplot/psy-maps/pull/36)
-   A bug has been resolved that crash makes unstructured plots fill the entire area on zooming in, see [#40](https://github.com/psyplot/psy-maps/pull/40)
-   psy-maps is now compatible with cartopy 0.19 and 0.20

Added
-----

-   psy-maps does now have a CITATION.cff file, see <https://citation-file-format.github.io>

Changed
-------

-   Documentation is now hosted with Github Pages at <https://psyplot.github.io/psy-maps>. Redirects from the old documentation at https://psy-maps.readthedocs.io have been configured.
-   Examples have been removed from the psy-maps repository as they now live in a central place at <https://github.com/psyplot/examples>
-   We use CicleCI now for a standardized CI/CD pipeline to build and test the code and docs all at one place, see [#35](https://github.com/psyplot/psy-maps/pull/35)

* do not set clip path for cartopy>=0.18

* update changelog with fix for #37

* replace RTD everywhere

* use psyplot-ci-orb@1.5.24

* minor fix for test instructions

* fix copyright

* fix email