fix: set QT_API to pyside6 or pyside2 for deadline-cli

[epmog]

What was the problem/requirement? (What/Why)

If a user has PyQt5/6 installed in their environment, launching the gui from the deadline client cli will throw an error saying TypeError: 'f' is an unknown keyword argument. This is because PyQt5/6 does not define f as a keyword arg in the QDialog constructor, even though Qt, PySide2, and PySide6 do.

This error will occur even if PySide6 or PySide2 are in the environment.

What was the solution? (How)

For now, set the QT_API environment variable to use/prioritize our supported Qt bindings.

ref: https://github.com/spyder-ide/qtpy/tree/master?tab=readme-ov-file#requirements

Can always add PyQt5/6 support in the future if needed.

What is the impact of this change?

Users with additional dependencies in their environment will continue to work!

How was this change tested?

Before the fix:

hatch shell
pip install PyQt5 PySide6
deadline config gui

received this error, since f is not a keyword for a QDialog in PyQt5/6

After fix without changing environment:

deadline config gui

And the gui launched properly

Was this change documented?

N/A

Is this a breaking change?

Nope

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