Update Documentation and Devcontainer to python 3.13

[jarlhengstmengel]

Short description

After #4424 Python 3.13 is a mandatory. This PR updates the Devcontainer to 3.13 and updates our documentation that python 3.13 is required.

Proposed changes

• Bumps up Devcontainer to Python 3.13
• Updates docs
• Some Devcontainer tweeks: No standard loading of testdata after building the container (can cause issues with celery), standard activation of linkcheck listeners (default in the cms config)

Side effects

• None

Faithfulness to issue description and design

There are no intended deviations from the issue and design.

How to test

If you are using the devcontainer, rebuild it (VS code should prompt you to do so).
If you don't use devcontainer, maybe do a sanity check and check the changed docs.

Resolved issues

Fixes: -

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Pull Request Review Guidelines

[timobrembeck]

Thanks a lot! 👍

I found a last remainder in publiccode.yml#L59:

integreat-cms/publiccode.yml

Line 59 in 7061480

version: "3.11"

[jarlhengstmengel]

@timobrembeck applied your suggestions. Also found a outdated requirement in install.sh for required node version (18 instead of 22)

[timobrembeck]

Thanks for your changes 👍

[seluianova]

I don't use Testcontainers (I tried it, but it's somehow very slow, and I'm not sure what the problem is), the docs lgtm.