Mergify: fix release version label
Mergify: fix release version label

Check if release review is not applied for merged PR. If not, we use "release version missing" label.

andcor02/mbed-os,kjbracey-arm/mbed,kjbracey-arm/mbed,andcor02/mbed-os,kjbracey-arm/mbed,kjbracey-arm/mbed,andcor02/mbed-os,mbedmicro/mbed,andcor02/mbed-os,mbedmicro/mbed,andcor02/mbed-os,mbedmicro/mbed,andcor02/mbed-os,mbedmicro/mbed,mbedmicro/mbed