Update explicit dependencies with discrepancies found by conda-forge bot

[rhugonnet]

geopandas was listed but unused
numpy, fiona, shapely and autovizwidget (not imported but used for plotting in the gallery examples) were used but not listed

Ran into a strange numba error on the first CI run, now gone... I remember having this issue 6 months ago already, which also disappeared by itself.
It's quite incomprehensible, so I added a point in the wiki:

5. The baffling: numba sometimes does not recognized expressions such as sum (e.g., https://github.com/GlacioHack/xdem/runs/7742646090?check_suite_focus=true) while clearly supported (https://numba.readthedocs.io/en/stable/reference/pysupported.html?highlight=sum). Probably because of a slightly different environment setup by mamba, but still... The one who solves that one will get a cake.

Resolves #273

[adehecq]

Great !