chore(deps): bump actions/setup-python from 4 to 6

Bumps [actions/setup-python](https://github.com/actions/setup-python) from 4 to 6.
- [Release notes](https://github.com/actions/setup-python/releases)
- [Commits](actions/setup-python@v4...v6)

---
updated-dependencies:
- dependency-name: actions/setup-python
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Use Py_REFCNT instead of ob_refcnt in generated code

- ob_refcnt is not guaranteed to be there

CI: Generate wrappers for Qt 6.8

Fix build with Python 3.13 (MeVisLab#246)

* Fix build with Python 3.13, fixes MeVisLab#245
* Update build.yml to python 3.13

reintroduce the runJavaScript method on QWebEnginePage for Qt 6

albeit without the callback parameter so far

Check for duplicates at one more place

(should fix compare methods generated twice for Qt 5.12/5.15)

Add support for Qt 6.7

- use Qt 6.7 for Winodws CI build, 6.6 for ubuntu
  (jurplel/install-qt-action has a problem with that version)
- fixes MeVisLab#215

Allow to set and get the render API in QQuickWindow

Update generator/main.cpp