Add missing widgets package to setup.py

[Smjert]

The setup.py file is missing the widgets package/directory.

When beeref is installed through that, it fails to start:

Traceback (most recent call last):
  File "/usr/bin/beeref", line 33, in <module>
    sys.exit(load_entry_point('BeeRef==0.3.2', 'gui_scripts', 'beeref')())
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/bin/beeref", line 25, in importlib_load_entry_point
    return next(matches).load()
           ^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/importlib/metadata/__init__.py", line 202, in load
    module = import_module(match.group('module'))
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.11/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<frozen importlib._bootstrap>", line 1204, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1176, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1147, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 690, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 940, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "/usr/lib/python3.11/site-packages/beeref/__main__.py", line 30, in <module>
    from beeref.view import BeeGraphicsView
  File "/usr/lib/python3.11/site-packages/beeref/view.py", line 30, in <module>
    from beeref import widgets
ImportError: cannot import name 'widgets' from 'beeref' (/usr/lib/python3.11/site-packages/beeref/__init__.py)

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (371e2e1) 97.19% compared to head (ca3a395) 97.19%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #88 +/- ## ======================================= Coverage 97.19% 97.19% ======================================= Files 25 25 Lines 2959 2959 ======================================= Hits 2876 2876 Misses 83 83 ```

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[rbreu]

Thanks for catching this! I really need so see if I can integrate some sort of test into the pipelines.