mutiple versions of puppet

Hello,
we uptating from puppet v3 to v7. Therefore we got two versions in paralell running which I want to check.
Gitlab itself is already client of the new system and therefore puppet v7.4 is installed. Checking puppet 7 pre-recive code is working fine , however puppet v3 always reject because of errors within the changed file. Any idear how I can handle multible versions of puppet sysntax?