Soft-Deprecate `assertContainsOnly()` and `assertNotContainsOnly()`

[sebastianbergmann]

[GuySartorelli]

Is there a suggestion of what should be used instead?

[sebastianbergmann]

Sure: https://github.com/sebastianbergmann/phpunit/blob/11.5/DEPRECATIONS.md#soft-deprecations

[GuySartorelli]

Thanks. I got to this issue because the deprecation notice in my IDE linked here, so I assume others will also come here looking for answers ;p