scripts: ci: check_compliance.py: add BOOT_SERIAL_UART to ALLOWLIST

Add Kconfig option BOOT_SERIAL_UART, defined in the MCUboot module but
needed to be used in tests, to the UNDEF_KCONFIG_ALLOWLIST.

Signed-off-by: Johann Fischer <[email protected]>

Author: jfischer-no

scripts/ci/check_compliance.py

@@ -1213,6 +1213,7 @@ def check_no_undef_outside_kconfig(self, kconf):
         "BOOT_SERIAL_CDC_ACM",       # Used in (sysbuild-based) test
         "BOOT_SERIAL_ENTRANCE_GPIO", # Used in (sysbuild-based) test
         "BOOT_SERIAL_IMG_GRP_HASH",  # Used in documentation
+        "BOOT_SERIAL_UART",          # Used in (sysbuild-based) test
         "BOOT_SHARE_BACKEND_RETENTION", # Used in Kconfig text
         "BOOT_SHARE_DATA",           # Used in Kconfig text
         "BOOT_SHARE_DATA_BOOTINFO", # Used in (sysbuild-based) test