Updated h3==3.7.7 to h3==4.1.2

[jeronimoluza]

This pull request is to update the polyfill of the geometries to hexagons using the latest H3 library.
I tested the example in the README.md and the behavior is still the expected.

A few minor changes:

• I updated the requirements.txt so it now installs version h3==4.1.2.

• Some scripts (urbanpy/geom/geom.py and urbanpy/utils/utils.py) were using old h3 imports: from h3 import h3.

  • I changed those to just import h3.

• The example in the README.md was wrong:

  • up.geom.gen_hexagons(res, city) is supposed to return a geopandas.GeoDataFrame with the hexagons and the geometries. The example was doing something like hexs, hex_centroids = up.geom.gen_hexagons(res, city), which is not how the function is used.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[jeronimoluza]

I also changed a call to an h3 library function from the resolution_downsampling() function. This was causing the tests not to pass.
@Claudio9701 everything ready!