Test integration tests

[certik]

This CI test should download a specific lpython conda package (the latest version with explicit version set), then check out a specific version of lpython's repository, go into integration tests and run them.

When we release a new lpython version, we tag the lpython repository, we create a new conda package. Then we'll come here and update the lpython conda package version + lpython repository version, and send a PR. All tests should pass.

If they fail, we figure out why, and fix it in upstream lpython. Release a new version, update conda and try again.

[ubaidsk]

Release a new version, update conda and try again.

Would it be fine if it works in a few tries? For example, there would be a few releases (released in a short span of time) which might fail.

[certik]

Yes. That's the workflow.