Use embassy/defmt-timestamp-uptime in all examples.

examples/stm32u5/src/bin/boot.rs

@@ -2,9 +2,9 @@
 #![no_main]
 #![feature(type_alias_impl_trait)]
 
-#[path = "../example_common.rs"]
-mod example_common;
-use example_common::*;
+use defmt::*;
+use defmt_rtt as _; // global logger
+use panic_probe as _;
 
 use embassy_stm32 as _;