(Feature): QT6 Support ?

[Martinfx]

Make sure to follow our issue report guidelines

• I have read the feature request guidelines
• I have followed the contributing guidelines to the best of my understanding
• This feature is not on the issue tracker and is not a duplicate

Provide a description of your feature request

Are you going to add support for QT6 ?

Is this a realistically implementable feature?

• My feature is realistically implementable
• My feature is NOT realistically implementable

Can you contribute in creating this feature?

• I am unable, or not willing to contribute to creating this feature
• I am able and willing to contribute to the creation of this feature

Additional details

I can test on FreeBSD OS. I ported last version Natron on FreeBSD with qt5.