Deprecation warnings in asyncio with Python 3.8

[dmajda]

When using aiopg with Python 3.8 with warnings enabled, deprecation warnings are emitted at various places where a loop argument is passed to asyncio APIs. To quote from What’s New In Python 3.8:

In asyncio, the explicit passing of a loop argument has been deprecated and will be removed in version 3.10 for the following: asyncio.sleep(), asyncio.gather(), asyncio.shield(), asyncio.wait_for(), asyncio.wait(), asyncio.as_completed(), asyncio.Task, asyncio.Lock, asyncio.Event, asyncio.Condition, asyncio.Semaphore, asyncio.BoundedSemaphore, asyncio.Queue, asyncio.create_subprocess_exec(), and asyncio.create_subprocess_shell().

It would be good to fix these warnings. I’m not sure whether it would involve just refactoring few asyncio API calls, or whether it would require deeper changes in loop handling inside the library.

[vir-mir]

@dmajda hi! what version of aiopg are you using? in version 1.0.0explicit transfer has been replaced with get_running_loop

[dmajda]

We use 1.0.0. Here are some specific places where the warnings pop up:

• connection.py line 90
• connection.py line 207
• pool.py line 57

These were caught by a test suite of one of @energomonitor’s internal projects that uses aiopg (we have warnings enabled when running tests). There may be some more places which our test suite didn’t catch.

[vir-mir]

Thank. Yes. I think it will be necessary to do this.

[seedofjoy]

Done. Review, please

[Pliner]

Resolved by #642