Upgrade to cppyy 3

[saraedum]

Checklist

• [ ] Added an entry in doc/news/.
• [ ] Added a test/benchmark for this change.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (1f81e3f) 92.23% compared to head (13b9cbc) 92.19%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #265 +/- ## ========================================== - Coverage 92.23% 92.19% -0.05% ========================================== Files 105 105 Lines 2125 2126 +1 ========================================== Hits 1960 1960 - Misses 165 166 +1 ```

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[saraedum]

Part of #266 now.