Update 03_state_of_async_rust.md

Update regarding to new stabialized future (https://blog.rust-lang.org/2023/12/21/async-fn-rpit-in-traits.html)

src/01_getting_started/03_state_of_async_rust.md

@@ -40,9 +40,7 @@ language features and library support:
   details.
 
 Some language features you may be used to from synchronous Rust are not yet
-available in async Rust. Notably, Rust does not let you declare async
-functions in traits. Instead, you need to use workarounds to achieve the same
-result, which can be more verbose.
+available in async Rust.
 
 ## Compiling and debugging