Bump all integrations to Scala Native 0.5.x

[Gedochao]

Version(s)
81acfaf

Describe what needs to be done and why
Some integrations do not yet support Scala Native 0.5.x, which forces us to downgrade the default to 0.4.17 for the time being.
Those include:

• Mill
• Scala Test
• Munit
• ScalaTest
• uTest
• ScalaPy
• Scala Toolkit
• TypeLevel Toolkit

Is your feature request related to a past ticket or discussion?
#2862 (comment)

Additional context
This ticket might stay open for a long time, as we don't control these integrations getting the Scala Native 0.5.x bump upstream. We just should remember about removing the downgrade on our side when they're ready.

[adpi2]

The Scala Toolkit is now available on Scala Native 0.5.x: https://github.com/scala/toolkit/releases/tag/0.4.0