zephyr_commit_rules.py: Fix pylint warning by simplifying conditional
zephyr_commit_rules.py: Fix pylint warning by simplifying conditional

Non-empty sequences are truthy in Python, so len() can be skipped in
tests.

Fixes this pylint warning:

    scripts/gitlint/zephyr_commit_rules.py:115:11: C1801: Do not use
    `len(SEQUENCE)` to determine if a sequence is empty
    (len-as-condition)

Fixing warnings for a CI check.

Signed-off-by: Ulf Magnusson <01743f1c1deb1fe75271d62edb65757d98ac0bcb@nordicsemi.no>

Vudentz/zephyr,nashif/zephyr,galak/zephyr,nashif/zephyr,Vudentz/zephyr,nashif/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,Vudentz/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,finikorg/zephyr,Vudentz/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,Vudentz/zephyr,finikorg/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr