Rebuild 4: retire support for Pythons 3.6, 3.7 and 3.8, and add support for Python 3.13 via pin webob >=1.8.9 (second attempt)

[valeriupredoi]

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• [ ] Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

Trying to see if a new branch and a new PR unstucks conda forge, the first attempt in #27 still suffers from conda-feedstock build issues (not ours)

[valeriupredoi]

@conda-forge-admin, please rerender

[conda-forge-admin]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe/meta.yaml) and found it was in an excellent condition.
I do have some suggestions for making it better though...

For recipe/meta.yaml:

• No valid build backend found for Python recipe for package esgf-pyclient using pip. Python recipes using pip need to explicitly specify a build backend in the host section. If your recipe has built with only pip in the host section in the past, you likely should add setuptools to the host section of your recipe.

[valeriupredoi]

No valid build backend found for Python recipe for package esgf-pyclient using pip. Python recipes using pip need to explicitly specify a build backend in the host section. If your recipe has built with only pip in the host section in the past, you likely should add setuptools to the host section of your recipe.

You no speaky English, regro-bot? I did!

[valeriupredoi]

excellent! Then am closing #27 for good