Update dev environment to python 3.12

[JoerivanEngelen]

Fixes #1491

Description

Use python 3.12 in dev environment.

2 issues had to be resolved:

• There is an issue with the pytest 8.4.0 i.c.w. pytest cases. Therfor i have pinned pytest until it gets resolved
  (AttributeError: 'MiniMetafunc' object has no attribute '_params_directness' (pytest >= 8.4.0) smarie/python-pytest-cases#365)
• There was a racecondtion going on in the test_import_prj.py file. Several tests were downloading the iMOD5_model.zip through pooch at the same time. I resolved it by having the tests get the file by calling the imod5_projectfile_data. This method has a filelock to prevent race conditions

Original errors:

ERROR test_formats\test_idf.py - AttributeError: 'MiniMetafunc' object has no attribute '_params_directness'
ERROR test_mf6\test_import_prj.py - PermissionError: [WinError 32] The process cannot access the file because it is being used by another process
ERROR test_mf6\test_mf6_regrid_scheme.py - AttributeError: 'MiniMetafunc' object has no attribute '_params_directness'

Checklist

• Links to correct issue
• Update changelog, if changes affect users
• PR title starts with Issue #nr, e.g. Issue #737
• Unit tests were added
• If feature added: Added/extended example

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[JoerivanEngelen]

Updating to pytest-xdist 3.7.0 unfortunately didn't resolve the issues.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[JoerivanEngelen]

Thanks @Manangka for fixing! Ready to merge, the failing unittest is a performance test which is slightly flaky.