MDA installation fails

[orbeckst]

All package installation workflows fail at the install-test-deps stage because they cannot resolve the mdanalysis conda-forge packages.

Resolving Environment                                                                           ⧖ Starting
Resolving Environment                                                                     ✔ Done (2.0 sec)
error    libmamba Could not solve for environment specs
    The following packages are incompatible
    ├─ mdanalysis =* * does not exist (perhaps a typo or a missing channel);
    └─ mdanalysistests =* * does not exist (perhaps a typo or a missing channel).
critical libmamba Could not solve for environment specs
Error: Process completed with exit code 1.

Eg https://github.com/MDAnalysis/MDAKits/actions/runs/25981191460/job/76370122439#step:8:40

There's been some evidence that there's an issue with choosing mamba as the miniconda package manager, e.g., possibly related: MDAnalysis/install-mdanalysis#11 so one attempt is to at least temporarily use conda+libmamba.

[IAlibay]

Should be fixed with #378

This was indeed an issue specific to the 2.6.0 release of mamba when handling uppercase package names. The issue has been fixed in newer bugfix releases but these haven't been exposed to the relevant github actions that we use to install mamba.