Use async/await keywords in test_server_asyncio.py

[JamesJeffryes]

I'm planning on splitting up a fix to #513 & #467 into a couple of PRs as there's more edits than I expected.

While I was replacing the old async syntax, I took a moment to do some reformatting, remove unused imports and replace the unittest methods with pytest syntax.

[dhoomakethu]

@JamesJeffryes Thanks for the PR, looks like this is breaking tests in all other python versions except 3.8. Would you be able to take a look please ?

[sonarqubecloud]

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13.3% Duplication

[JamesJeffryes]

Fixed most of the other builds by specifying a minimum version of 'attrs' but the xcode tests looks like they are timing out trying to install java. Maybe there's a more modern image that could be used?

[JamesJeffryes]

More general question, if this code is bound for a 3.5+ release. Should I pull out the IS_PYTHON3 checking in the tests as I go?

[JamesJeffryes]

@dhoomakethu Thoughts on the failing xcode build?

[dhoomakethu]

Will take a look, osx builds are failing off late. Could be the xcode version that is causing the issue.

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!

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0 Security Hotspots
0 Code Smells

No Coverage information
No Duplication information