tests: drivers: i2c: i2c_target_api: update testcase file

add stm32n6570_dk in yaml file for CI test integration
purpose.


Signed-off-by: Fabrice DJIATSA <[email protected]>

Author: djiatsaf-st

tests/drivers/i2c/i2c_target_api/testcase.yaml

@@ -17,6 +17,7 @@ tests:
       - stm32f072b_disco
       - stm32f3_disco
       - stm32h573i_dk
+      - stm32n6570_dk/stm32n657xx/sb
       - stm32u083c_dk
       - nucleo_c071rb
       - nucleo_g071rb