v1.2.3 to fix DutyCycle bug, etc.

### Releases v1.2.3

1. Fix `DutyCycle` bug. Check [float precisison of DutyCycle only sometimes working #3](khoih-prog/SAMD_Slow_PWM#3)
2. Fix `New Period` display bug. Check [random dropouts #4](khoih-prog/SAMD_Slow_PWM#4)
3. Update examples

Author: khoih-prog

CONTRIBUTING.md

@@ -31,7 +31,7 @@ Arduino IDE version: 1.8.19
 STM32 Core Version 2.2.0
 Nucleo-144 STM32H7 NUCLEO_H743ZI2
 OS: Ubuntu 20.04 LTS
-Linux xy-Inspiron-3593 5.4.0-96-generic #109-Ubuntu SMP Wed Jan 12 16:49:16 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
+Linux xy-Inspiron-3593 5.4.0-100-generic #113-Ubuntu SMP Thu Feb 3 18:43:29 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
 
 Context:
 I encountered a crash while using TimerInterrupt.