Remove Linux-only PyGObject and qtpy from requirements.txt

[AlizerUncaged]

Summary

• Removed PyGObject and qtpy from requirements.txt
• These are Linux-only dependencies for pywebview's GTK/Qt backend
• On Windows, pywebview uses WebView2, and these packages fail to build from source during setup.bat / setup.ps1, breaking installation

Error on Windows

Running setup.ps1 or setup.bat fails with:

ERROR: Exception:
Traceback (most recent call last):
  File "...\pip\_internal\cli\base_command.py", line 107, in _run_wrapper
    status = _inner_run()
  File "...\pip\_internal\cli\base_command.py", line 98, in _inner_run
    return self.run(options, args)
  File "...\pip\_internal\commands\install.py", line 392, in run
    requirement_set = resolver.resolve(
  File "...\pip\_internal\resolution\legacy\resolver.py", line 184, in resolve
    discovered_reqs.extend(self._resolve_one(requirement_set, req))
  File "...\pip\_internal\resolution\legacy\resolver.py", line 506, in _resolve_one
    dist = self._get_dist_for(req_to_install)
  File "...\pip\_internal\resolution\legacy\resolver.py", line 459, in _get_dist_for
    dist = self.preparer.prepare_linked_requirement(req)
  File "...\pip\_internal\operations\prepare.py", line 542, in prepare_linked_requirement
    return self._prepare_linked_requirement(req, parallel_builds)
  File "...\pip\_internal\operations\prepare.py", line 657, in _prepare_linked_requirement
    dist = _get_prepared_distribution(
  File "...\pip\_internal\operations\prepare.py", line 77, in _get_prepared_distribution
    abstract_dist.prepare_distribution_metadata(
  File "...\pip\_internal\distributions\sdist.py", line 55, in prepare_distribution_metadata
    self._install_build_reqs(build_env_installer)
  File "...\pip\_internal\distributions\sdist.py", line 132, in _install_build_reqs
    build_reqs = self._get_build_requires_wheel()
  File "...\pip\_internal\distributions\sdist.py", line 107, in _get_build_requires_wheel
    return backend.get_requires_for_build_wheel()

PyGObject requires GTK development libraries and cannot build from source on Windows. qtpy is also unnecessary since pywebview uses WebView2/EdgeChromium on Windows, not GTK or Qt.

Test plan

• Run setup.bat or setup.ps1 on Windows — should complete without errors
• Run setup.sh on Linux — pywebview should still work (it installs GTK deps via system packages, not pip)
• Launch the GUI with run.bat / run.sh and verify it opens correctly