raise a ValueError when user tries to delete an unexisting transform

[Gautzilla]

This PR adds a ValueError raising if Project.delete_transform_with_outputs() is called with an unexisting transform name:

project.delete_transform_with_outputs("Maellezilla")

Traceback (most recent call last):
  File "C:\Users\berthoga\Documents\GitHub\OSEkit\.venv\Lib\site-packages\IPython\core\interactiveshell.py", line 3701, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
    ~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<ipython-input-10-438fc50a0a98>", line 1, in <module>
    project.delete_transform_with_outputs("Maellezilla")
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^
  File "C:\Users\berthoga\Documents\GitHub\OSEkit\src\osekit\public\project.py", line 749, in delete_transform_with_outputs
    raise ValueError(message)
ValueError: Transform 'Maellezilla' not found.

resolves #370

[coveralls]

coverage: 98.841% (+0.002%) from 98.839% — Gautzilla:unexisting-output-deletion-warning into Project-OSmOSE:main