Update Config File or Env Variable on build

I'm using pipelines in a PHP (Laravel) project.

I need to run phpunit and in some tests I can't have the same number (because we are trying to send documents to the government in a test enviroment.

We tried to use a configuration file, but the problem is that I have to commit this update and the pipeline will run again because of this commit (loop).

We tried to use env variable from pipelines settings, but the problem is that the env variable is not updating with putenv().

May putenv() update the env variable?
Is there any alternative way to do what I explained?

Thank you.