Adjust test suite to JPype1.5.1

[glatterf42]

JPype1 just released their version 1.5.1, which now supports Python 3.13 :)
Unfortunately, it also broke our CI test suite, but only two parts that we initially adjusted for Python 3.12 and JPype1 1.5.0, so this PR simply reverts these changes, hoping it should let the tests pass again.

How to review

• Read the diff and note that the CI checks all pass.

PR checklist

• Continuous integration checks all ✅
• Update tests; coverage checks both ✅
• [ ] Add, expand, or update documentation. Just test adjustment.
• [ ] Update release notes. Just test adjustment.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.9%. Comparing base (02c887a) to head (352cd7b).
Report is 14 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #550     +/-   ##
=======================================
- Coverage   98.9%   98.9%   -0.1%     
=======================================
  Files         44      44             
  Lines       4819    4816      -3     
=======================================
- Hits        4769    4765      -4     
- Misses        50      51      +1     

Files with missing lines	Coverage Δ
ixmp/tests/core/test_scenario.py	100.0% <ø> (ø)
ixmp/tests/test_cli.py	100.0% <100.0%> (ø)

... and 1 file with indirect coverage changes

---- 🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests

[khaeru]

Is this the last thing we were waiting on to complete and merge #544? Can we maybe cherry-pick this commit onto the branch for that PR and rebase it?

[glatterf42]

Not so sure: I tried what you suggested, but we still see error messages from bottle and pretenders. These might come down to pretenders/pretenders#153, i.e. pretenders not being maintained anymore, while the latest bottle version actually supports Python 3.13. I'm not too sure what we can do about that.
To get the CI to pass again tomorrow, I'd be in favor of merging this PR first.

[khaeru]

These might come down to pretenders/pretenders#153, i.e. pretenders not being maintained anymore, while the latest bottle version actually supports Python 3.13. I'm not too sure what we can do about that.

This one wasn't in the description of #544, so reading the description I had the wrong impression that all upstream issues were resolved. I'll add it now.

[glatterf42]

Superseded by #544.