Support Python 3.13

[valeriupredoi]

Description

Sister PR to https://github.com/ESMValGroup/ESMValCore/pull/2566

so far the major bottleneck is ncl which has an autoPR for upgrade to newer proj https://github.com/conda-forge/ncl-feedstock/pull/156 but that fails atm due to inconsistencies in conda-forge

---

Before you get started

• [x] ☝ Create an issue to discuss what you are going to do

Checklist

It is the responsibility of the author to make sure the pull request is ready to review. The icons indicate whether the item will be subject to the 🛠 Technical or 🧪 Scientific review.

• [x] 🛠 This pull request has a descriptive title
• [x] 🛠 Code is written according to the code quality guidelines
• [x] 🛠 Any changed dependencies have been added or removed correctly
• [ ] 🛠 All checks below this pull request were successful

[valeriupredoi]

OK I removed ncl for now (clearly a blocker, noqa), we need to rebuild pys2index for py3.13; next hurdle psy- packages!