[bug]: kapitan v0.34.0-rc.0 pip and friends does not install required dependency reclass_rs

[antonincms]

Description of the bug

If I install kapitan v0.34.0-rc.0 with the default set of dependency it crashes, but works perfectly if I install reclass_rs.

Steps to reproduce

# If we use the default installation of kapitan it crashes :
❯ pipx install kapitan@git+https://github.com/kapicorp/kapitan@v0.34.0-rc.0 --python=python3.10
  installed package kapitan 0.34.0rc0, installed using Python 3.10.14
  These apps are now globally available
    - kapitan
done! ✨ 🌟 ✨

❯ kapitan --version
Traceback (most recent call last):
  File "/Users/user/.local/bin/kapitan", line 5, in <module>
    from kapitan.cli import main
  File "/Users/user/.local/pipx/venvs/kapitan/lib/python3.10/site-packages/kapitan/cli.py", line 23, in <module>
    from kapitan.inputs.jsonnet import jsonnet_file
  File "/Users/user/.local/pipx/venvs/kapitan/lib/python3.10/site-packages/kapitan/inputs/jsonnet.py", line 16, in <module>
    from kapitan.resources import resource_callbacks, search_imports
  File "/Users/user/.local/pipx/venvs/kapitan/lib/python3.10/site-packages/kapitan/resources.py", line 26, in <module>
    from kapitan.inventory import Inventory, ReclassInventory, AVAILABLE_BACKENDS
  File "/Users/user/.local/pipx/venvs/kapitan/lib/python3.10/site-packages/kapitan/inventory/__init__.py", line 4, in <module>
    from .inv_reclass_rs import ReclassRsInventory
  File "/Users/user/.local/pipx/venvs/kapitan/lib/python3.10/site-packages/kapitan/inventory/inv_reclass_rs.py", line 3, in <module>
    import reclass_rs
ModuleNotFoundError: No module named 'reclass_rs'

# But if we install reclass_rs in the venv of kapitan it works :
❯ pipx inject kapitan reclass_rs
  injected package reclass-rs into venv kapitan
done! ✨ 🌟 ✨

❯ kapitan --version
0.34.0-rc.0

Version (kapitan)

v0.34.0-rc.0

Version (python)

3.10

Python virtual environment

• pyenv
• venv
• pipx
• no environment

OS information

macOS

[antonincms]

It seems the issue is that reclass_rs is required but still considered optional by pip / pipx / uv.
I tracked it down to the mention of the dependency in extras, I think this PR should fix it.
Another possibility could be to make this dependency optional and handle the case where it is not installed.