Fix #5169 - Mark ArgumentsProvider provideArguments(ParameterDeclarations) as MAINTAINED instead of EXPERIMENTAL.

[Vishalup29]

Fixes #5169

This PR updates the API status of the new overload of
ArgumentsProvider.provideArguments(ParameterDeclarations, ExtensionContext)
from EXPERIMENTAL to MAINTAINED.

Background

In JUnit Jupiter 6.0.1, the new provideArguments(ParameterDeclarations, ExtensionContext) method is marked as @API(status = EXPERIMENTAL) while the older provideArguments(ExtensionContext) method is already deprecated.

This creates a mismatch:

• Users are encouraged to migrate to the new method
• But the new method is still labeled experimental
• Spring Boot 4.0.0 surfaced this inconsistency during upgrade

As noted in the issue discussion, the maintainers confirmed that the new API is stable and should be treated as maintained starting with JUnit 6.0.2.

Summary of Changes

Update the annotation on
provideArguments(ParameterDeclarations parameters, ExtensionContext context)
from:

@API(status = EXPERIMENTAL, since = "6.0")

to:

@API(status = MAINTAINED, since = "6.0")

This aligns the API status with the maintainer guidance and resolves the confusion around the intended stability level of the new method.

Rationale

• The new overload is the recommended migration target, replacing the deprecated method
• Marking it as MAINTAINED ensures tools, users, and downstream projects treat it as stable
• Brings the declaration in line with the milestone notes for 6.0.2)

[mpkorstanje]

Thanks for offering to contribute. However we will pick this up ourselves. The change is simple enough that it doesn't warrant the overhead of a back-and-forth over a pull request.

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