Update pyproject.toml to work with Poetry v2

[CTassisF]

mnogu/chitose will not build with Poetry v2 due to changes in pyproject.toml:

% pip3 install -U -r backend/requirements.txt
Collecting chitose@ git+https://github.com/mnogu/chitose (from -r backend/requirements.txt (line 2))
  Cloning https://github.com/mnogu/chitose to /private/var/folders/01/y8z_y8wx75g7x9s27j8x21sh0000gn/T/pip-install-l7z5k28w/chitose_eb8d62e206364be7bad4193827384ab6
  Running command git clone --filter=blob:none --quiet https://github.com/mnogu/chitose /private/var/folders/01/y8z_y8wx75g7x9s27j8x21sh0000gn/T/pip-install-l7z5k28w/chitose_eb8d62e206364be7bad4193827384ab6
  Resolved https://github.com/mnogu/chitose to commit d1dcfea0995b6f3dc62d83db7138b1112335a26e
  Running command git submodule update --init --recursive -q
  Installing build dependencies ... done
  Getting requirements to build wheel ... done
  Preparing metadata (pyproject.toml) ... error
  error: subprocess-exited-with-error
  
  × Preparing metadata (pyproject.toml) did not run successfully.
  │ exit code: 1
  ╰─> [16 lines of output]
      Traceback (most recent call last):
        File "/Users/<REDACTED>/env/lib/python3.13/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 353, in <module>
          main()
          ~~~~^^
        File "/Users/<REDACTED>/env/lib/python3.13/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 335, in main
          json_out['return_val'] = hook(**hook_input['kwargs'])
                                   ~~~~^^^^^^^^^^^^^^^^^^^^^^^^
        File "/Users/<REDACTED>/env/lib/python3.13/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 149, in prepare_metadata_for_build_wheel
          return hook(metadata_directory, config_settings)
        File "/private/var/folders/01/y8z_y8wx75g7x9s27j8x21sh0000gn/T/pip-build-env-ci0rv1yr/overlay/lib/python3.13/site-packages/poetry/core/masonry/api.py", line 42, in prepare_metadata_for_build_wheel
          poetry = Factory().create_poetry(Path().resolve(), with_groups=False)
        File "/private/var/folders/01/y8z_y8wx75g7x9s27j8x21sh0000gn/T/pip-build-env-ci0rv1yr/overlay/lib/python3.13/site-packages/poetry/core/factory.py", line 58, in create_poetry
          raise RuntimeError("The Poetry configuration is invalid:\n" + message)
      RuntimeError: The Poetry configuration is invalid:
        - project must contain ['name'] properties
      
      [end of output]
  
  note: This error originates from a subprocess, and is likely not a problem with pip.
error: metadata-generation-failed

× Encountered error while generating package metadata.
╰─> See above for output.

note: This is an issue with the package mentioned above, not pip.
hint: See above for details.

This PR fixes the issues in pyproject.toml.