H3ronpy

- Dependency upgrades incl. upgrade to H3 v4.0.0 / h3ron v0.15.0.
- The migration to H3 v4.0.0 comes with renaming a few functions to follow H3 conventions:
- In `h3ronpy.op` module:
- `kring_distances` -> `grid_disk_distances`
- `kring_distances_agg` -> `grid_disk_distances_agg`
- `kring_distances_agg_np` -> `grid_disk_distances_agg_np`

Added
- Add `h3ronpy.op.change_resolution` and `h3ronpy.op.change_resolution_paired`

Changed
- Replace usage of `wkb` crate with `geozero` because of licensing.
- Stop supporting Python 3.6 (was EOL on 23 Dec 2021). Minimum supported python version now is Python 3.7.
- Omit empty geometries when converting vector data.
- Dependency upgrades.

Added
- Building wheels for Windows and Mac using github actions.

Added
- `h3ronpy.op.kring_distances` and `h3ronpy.op.kring_distances_agg`.

Changed
- The python extension has been removed from this repository and moved to its own repository at
[github.com/nmandery/h3ronpy](https://github.com/nmandery/h3ronpy).
- Upgrade h3ron dependency to 0.13, h3ron-ndarray to 0.13.
- Upgrade `pyo3` and `rust-numpy` dependencies to 0.15.
- Raise `geopandas` version requirement from 0.8 to 0.10.