Picking a specific python version when building ray locally

I’m running into a version mismatch for a ray cluster I built with Building Ray from Source — Ray v1.8.0
where after I start the server in java, and I’m getting

<class 'RuntimeError'>: Version mismatch: The cluster was started with:
    Ray: 1.7.1
    Python: 3.8.5
This process on node was started with:
    Ray: 1.7.1
    Python: 3.9.7

How do I build the ray cluster locally with a specific python version such such that I can create jars with the expected python version? I am using build-jar-multiplatform.sh to create the jars

note that when I built the project locally, there is a ray binary created inside the python environment bin folder, and starting the cluster with this binary (ray start..) works.