[Feature Request] openfga version endpoint

[corbinschrumpf]

I am not able to find an endpoint (or other way) to determining what openfga version we are running. If something like this doesn't already exist I would like to request that we add the version (Currently: v0.3.7) to the healthz endpoint or an additional endpoint. This would allow us to confirm what version we are running and also use that version for future use.

Healthcheck:
curl -X GET localhost/healthz