MNT: Remove mentions of GDAL

[greglucas]

It isn't used anywhere within Cartopy and can be handled by other libraries.

[QuLogic]

What about requirements/plotting.txt?

[greglucas]

Oops, I had changed it, but forgot to save the file before committing. Thanks for catching that!

[dopplershift]

I'm not finding any more with grep now.

[amotl]

Dear Greg,

we appreciate the removal of the GDAL dependency from Cartopy very much. Because we are currently blocked at earthobservations/wetterdienst#878 and earthobservations/wetterdienst#879, it would be so lovely to rebase this work on top of a new Cartopy release, which will not pull in GDAL. Is there anything you could do about it? 🌻

With kind regards,
Andreas.

[greglucas]

This PR should have been mostly a "documentation" change and not a code/requirement change. GDAL only comes in via pip install -r requirements/plotting.txt or through the environment.yaml, so my guess is that the GDAL dependency comes from somewhere else for you (Fiona?).

[amotl]

Hi Greg,

thank you very much for clarifying. You are right, GDAL does not get pulled in by Cartopy, but by wradlib-1.18.0 instead, despite it is being listed as optional ¹.

Sorry for the noise and with kind regards,
Andreas.

Footnotes

1. https://github.com/wradlib/wradlib/blob/1.18.0/requirements_optional.txt#L3 ↩