Update wheels to 0.8.0dev2

[richardliaw]

What do these changes do?

Updates the wheels to latest version of master.

Related issue number

Linter

• I've run scripts/format.sh to lint the changes in this PR.

[robertnishihara]

Thanks @richardliaw! There may be other occurrences of 0.8.0.dev1 in the codebase that should be changed as well. E.g., in some autoscaler configs and test scripts.

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