Fix minimum required platformdirs version

[spike77453]

This sets the minimum required platformdirs version to 3.2.0 since ensure_exists does not exists before 3.2.0: https://github.com/platformdirs/platformdirs/commit/fd0172a3a375c53737cade44cb6155ac8f243344

ensure_exists is used in the following places:

• https://github.com/30350n/inventree_part_import/blob/8dcd9dcaa901c33ecddf1f0c4767363491fff0b8/inventree_part_import/inventree_helpers.py#L20
• https://github.com/30350n/inventree_part_import/blob/8dcd9dcaa901c33ecddf1f0c4767363491fff0b8/inventree_part_import/suppliers/supplier_digikey.py#L12

This prevents TypeError: user_cache_path() got an unexpected keyword argument 'ensure_exists' when running inventree_part_import in environments with older versions of platformdirs installed.

[30350n]

Great, thanks for the fix!