Fix never awaited coroutines to close

[fregataa]

What do these changes do?

utils._AsyncCM objects have a _coro coroutine type field. In some cases, it is not awaited and it raises RuntimeWarning like below

RuntimeWarning: coroutine 'Docker._do_query' was never awaited

One of the suspicious parts is from Container.log(). Let's close the coroutine if any error occurs.

Are there changes in behavior for the user?

They will not see RuntimeWarning anymore!

Related issue number

Checklist

• [x] I think the code is well written
• [x] Unit tests for the changes exist
• [x] Documentation reflects the changes
• [x] If you provide code modification, please add yourself to CONTRIBUTORS.txt
  • The format is <Name> <Surname>.
  • Please keep alphabetical order, the file is sorted by names.
• [x] Add a new news fragment into the changes folder
  • name it <issue_id>.<type> for example (588.bug)
  • if you don't have an issue_id change it to the pr id after creating the pr
  • ensure type is one of the following:
  • .feature: Signifying a new feature.
  • .bugfix: Signifying a bug fix.
  • .doc: Signifying a documentation improvement.
  • .removal: Signifying a deprecation or removal of public API.
  • .misc: A ticket has been closed, but it is not of interest to users.
  • Make sure to use full sentences with correct case and punctuation, for example: "Fix issue with non-ascii contents in doctest text files."

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 75.00000% with 3 lines in your changes missing coverage. Please review.

Project coverage is 81.25%. Comparing base (906d8c5) to head (f7a9476).

:exclamation: Current head f7a9476 differs from pull request most recent head 4e85c33

Please upload reports for the commit 4e85c33 to get more accurate results.

Files	Patch %	Lines
aiodocker/containers.py	70.00%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #861 +/- ## ========================================== - Coverage 81.34% 81.25% -0.09% ========================================== Files 24 24 Lines 1372 1382 +10 Branches 245 245 ========================================== + Hits 1116 1123 +7 - Misses 170 173 +3 Partials 86 86 ```

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