Updating MExt to support python 3.12 syntax

[eirikurj]

Purpose

Per title. imp has been removed in python 3.12.

Expected time until merged

Once tests pass.

Type of change

• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (non-backwards-compatible fix or feature)
• [ ] Code style update (formatting, renaming)
• [ ] Refactoring (no functional changes, no API changes)
• [ ] Documentation update
• [ ] Maintenance update
• [ ] Other (please describe)

Testing

We currently dont run or test python 3.12, but if anyone has it installed, please test.

Checklist

• [ ] I have run flake8 and black to make sure the Python code adheres to PEP-8 and is consistently formatted
• [ ] I have formatted the Fortran code with fprettify or C/C++ code with clang-format as applicable
• [ ] I have run unit and regression tests which pass locally with my changes
• [ ] I have added new tests that prove my fix is effective or that my feature works
• [ ] I have added necessary documentation

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 92.85714% with 1 line in your changes missing coverage. Please review.

Project coverage is 79.24%. Comparing base (303a221) to head (ccc7a7a). Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
pyhyp/MExt.py	91.66%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #95 +/- ## ======================================= Coverage 79.24% 79.24% ======================================= Files 4 4 Lines 424 424 ======================================= Hits 336 336 Misses 88 88 ```

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