Bump webob to 1.8.10

[marcospri]

Remove it from requirements/requirements-prod.in, it's a transitive dependency via flanker.

Changelog is not great, see release history in pipy

• https://pypi.org/project/WebOb/#history

• Tags in Github gives us:

[1.8.10](https://github.com/Pylons/webob/releases/tag/1.8.10)
Merge commit from fork

Fix open redirect issue due to changes made in cPython >=3.10
 on Jun 2 [ b240857]


[1.8.9](https://github.com/Pylons/webob/releases/tag/1.8.9)
Add info for 1.8.9 fix for Python 3.13

1.8.10, released in june, fixes: https://github.com/closeio/sync-engine/security/dependabot/130