doc: add example, interval selection on a map

[mattijn]

This PR adds a new example showing how one can use the selection interval on a map:

ref: #1232

[mattijn]

@binste, do you know how I can avoid this mypy error?

error: Cannot find implementation or library stub 
for module named "geopandas"  [import-not-found]

[binste]

In the lint workflow, only normal and dev dependencies are being installed. geopandas is a doc dependency so far and hence, mypy can't find it. As we now use it in this example which is also a test, geopandas should be moved from doc dependencies to dev in pyproject.toml. As geopandas is not a typed package as far as I know, you'll first get another error:

tests/examples_methods_syntax/interval_selection_map_quakes.py:11: error: Skipping analyzing "geopandas": module is installed, but missing library stubs or py.typed marker  [import-untyped]

which you can solve by adding geopandas.* to the modules under [[tool.mypy.overrides]] in pyproject.toml.

These two steps should make mypy happy :)

[binste]

Great example! Could you harmonize the usage of single and double quotes to one of them (my preference is double quotes). Apart from that, looks good to me.

[mattijn]

Thanks for the review @binste. Applied your suggestions. Tests are happy, so merging.

[binste]

I like the idea of "happy" tests. Petition for GitHub to replace the red X and green check mark with grumpy and happy smilies ;)