Add support for python 3.13

[almet]

Python 3.13 is available since Oct. 7, 2024. The reason we don't support it is because PySide6 didn't support it yet. They announced support for Python 3.13 will be added in Pyside6 6.8. .

But... I've been able to run it locally with the latest pyside6==6.8.0.1 release, so I wonder if we could get away with it:

> uv venv .venv -p python3.13
> uv pip install pyside6
Resolved 4 packages in 892ms
Prepared 4 packages in 38.00s
Installed 4 packages in 35ms
 + pyside6==6.8.0.2
 + pyside6-addons==6.8.0.2
 + pyside6-essentials==6.8.0.2
 + shiboken6==6.8.0.2

And then running a small UI from their doc, here if you want:

import sys
import random
from PySide6 import QtCore, QtWidgets, QtGui


class MyWidget(QtWidgets.QWidget):
    def __init__(self):
        super().__init__()

        self.hello = ["Hallo Welt", "Hei maailma", "Hola Mundo", "Привет мир"]

        self.button = QtWidgets.QPushButton("Click me!")
        self.text = QtWidgets.QLabel("Hello World", alignment=QtCore.Qt.AlignCenter)

        self.layout = QtWidgets.QVBoxLayout(self)
        self.layout.addWidget(self.text)
        self.layout.addWidget(self.button)

        self.button.clicked.connect(self.magic)

    @QtCore.Slot()
    def magic(self):
        self.text.setText(random.choice(self.hello))


if __name__ == "__main__":
    app = QtWidgets.QApplication([])

    widget = MyWidget()
    widget.resize(800, 600)
    widget.show()

    sys.exit(app.exec())

We currently fallback on Pyside2 in our code, when PySide6 isn't installed, which should be the case on systems where Python is older than Python3.11. We would probably need to trick the debian and fedora package building scripts to replace the python 3.13 dep with something older.

[almet]

Our CI tests started failing due to our lack of support of python 3.13, as Debian Trixie switched python3-defaults to python3.13.1-2

At the same time, the Pyside6 version in Trixie is still < 6.8, and doesn't support python 3.13+

So, it seem that we'll need to find a way for our Debian packages to install python3 < 3.13

[apyrgio]

Woah, I hadn't realized that Debian has started shipping python3-pyside6. At last, that's amazing! I've captured the latest support matrix here: #211 (comment)

Regarding our issue, I think that the availability of python3-pyside6 does not change anything, because we don't use it, either in our prod or dev environments. We should start doing that though soon.

[apyrgio]

About supporting Python 3.13, we should have added a reminder here :-/. Turns out that with the latest PySide6 version in PyPI, it's as simple as bumping our upper bound on the Python version. Check out e388fe6.

Here are also the CI tests that pass with this change: https://github.com/freedomofpress/dangerzone/actions/runs/12988802826