Create an CI job that runs against the pre-built package

[chayim]

Much like redis-py, nredisstack builds a package. However, it's possible to release a broken version. To catch this we should have a job that:

1. Takes the pre-built package from a prior step
2. Installs and runs tests using it.

This is exactly the reason for this test in redis-py, and is generally something we should extend to all redis clients.