CI: update use of deprecated iteritems to avoid warnings

[m-richards]

Should fix the failing 310-dev environment, we're just now getting warnings from pandas-dev/pandas#45321

(the change in geoseries is not required to fix CI, but seemed sensible to get all at once)

I also noticed setting up a local environment that this environment doesn't actually seem to use numpy main, despite in being in the yaml:

geopandas/ci/envs/310-dev.yaml

Line 29 in cebb587

- --pre --extra-index https://pypi.anaconda.org/scipy-wheels-nightly/simple numpy

I'll make that a separate issue though.

[martinfleis]

Thanks!

[d3netxer]

The docs still list iteritems(), I made me think it was not depreciated.

https://geopandas.org/en/stable/docs/reference/api/geopandas.GeoSeries.html

[m-richards]

Hi @d3netxer, I think it's still expected that this should be listed in the docs - it hasn't been removed yet. In principle we could add a deprecation warning/ hide this method, but it's a little tricky to do in practice as that list of methods is auto-generated and iteritems itself is inherited from pandas.