Disposal is not called with use! and the like #157

It appears that Dispose() or DisposeAsync() is not being called when use! is used. First mentioned offline by @bartelink. Logging here to link the PR to a tracking issue and for the changelog/release notes.

Turned out that this was inadvertently commented out in 27486f3, which shouldn't have happened. In a follow up I will create some tests to ensure this won't happen again.