The following PR tackles a couple of related things.

• We have had some intermitent false warnings coming up when a Marker was using a Composable within it, see this issue. This was not consistent, and happened with different versions.
• The latest Kotlin version, 2.2.20, seems to induce this warning. So probably some new check on the compiler that makes this inference not smart enough to identify a Composable is happening within it. Tagging it with the UiComposable annotation fixes it (note: the two alternatives are UiComposable or VectorComposable, and we probably fall into the former variant).
• Also: Kotlin 2.2.20 deprecates a few things, so the PR cleans the warnings we are getting.

Fixes: #598