appveyor: fix PX4 version format check
appveyor: fix PX4 version format check

by removing shallow clone such that we can infer the version from the
last tag

PX4/Firmware,dagar/Firmware,PX4/Firmware,acfloria/Firmware,krbeverx/Firmware,krbeverx/Firmware,dagar/Firmware,krbeverx/Firmware,dagar/Firmware,acfloria/Firmware,acfloria/Firmware,acfloria/Firmware,krbeverx/Firmware,acfloria/Firmware,krbeverx/Firmware,dagar/Firmware,acfloria/Firmware,PX4/Firmware,PX4/Firmware,PX4/Firmware,dagar/Firmware,acfloria/Firmware,dagar/Firmware,PX4/Firmware,PX4/Firmware,krbeverx/Firmware,krbeverx/Firmware,dagar/Firmware