Preparation for Biotite 1.0/Numpy 2.0

[JHKru]

This PR will address the upcoming transition to Numpy 2.0.
Changes will be limited to tests/github workflows.

• explicitly restrict the Scipy version to <= 1.13.1. This version is compatible with Numpy 2.0, while retaining deprecated keywords in functions used by ProDy (such as "turbo" in linalg.eigh).
  Conda combines Numpy 1.26 with Scipy 1.14 currently, which fails in tests.
• check, whether rpy2 works as expected with Numpy 2.0 (after release of Biotite 1.0)

In case rpy2 is not compliant with Numpy 2.0, tests will have to be reverted to pre-run R scripts/resultant .csv files.

[JHKru]

Prody requires Numpy < 1.25, which is incompatible with Biotite (>= 1.25).

An inelegant solution:
We could add a separate test preparation conda environment with prody/rpy2/bio3d to produce .csv files and read these in
during our tests in the dev environment containing biotite >=1.0/Numpy>=2.0 (like for the tests prior to PR #14 ).
@padix-key: If you are fine with this, I'd close this PR and open a dedicated one for that purpose.

[padix-key]

Sounds like a good solution to me 👍