The ray-ml image depends on numpy ~=1.19.2 via the tensorflow==2.6 requirement. Unfortunately that's incompatible with Dataset (see here #20258 (comment)).
This PR upgrades the numpy dependency only for the nightly test.
* use nightly
* switch ml cpu to ray cpu
* fix
* add pytest
* add more pytest
* add constraint
* add tensorflow
* fix merge conflict
* add tblib
* fix
* add back uninstall
When testing it we should minimize unnecessary env vars (and it's better working with the default config). This PR removes unnecessary env vars that are set.