Revise the use of async from CE3 Async[F] in the light of new cancelation semantics introduced with CE3 3.5.0

[kamilkloch]

CE3 3.5.0 introduced new async cancelation semantics:
The changes in async cancelation (and particularly the implications on async_) are definitely expected to have user-facing impact, potentially breaking existing code in subtle ways. If you have any code which uses async_ (or async) directly, you should read this section very carefully and potentially make the corresponding changes.

https://github.com/typelevel/cats-effect/releases/tag/v3.5.0

Usages of Async[F]#async and Async[F]#async_ should be probably revised.