fix: use pathlib.Path for save_path

[rabii-chaarani]

Description

Fixes beartype error by adding pathlib path instead of string for MapData.save_mapdata_to_files method

Fixes #(issue)

Type of change

• Documentation update
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Test improvement

How Has This Been Tested?

Please describe any tests that you ran to verify your changes.
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Checklist:

• This branch is up-to-date with master
• All gh-action checks are passing
• I have performed a self-review of my own code
• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• My tests run with pytest from the map2loop folder
• New and existing tests pass locally with my changes

Checklist continued (if PR includes changes to documentation)

• I have built the documentation locally with make.bat
• I have built this documentation in docker, following the docker configuration in map2loop/docs
• I have checked my spelling and grammar