Added debug=2 in release profile to all examples.

This makes rtt output work right when using `cargo run` in release mode.

Debug was already enabled for release builds in some of the examples but
not all.

examples/stm32u5/Cargo.toml

@@ -23,3 +23,6 @@ futures = { version = "0.3.17", default-features = false, features = ["async-awa
 heapless = { version = "0.7.5", default-features = false }
 
 micromath = "2.0.0"
+
+[profile.release]
+debug = 2