Update supported docker version and clean tests a bit

[barrachri]

What do these changes do?

• Add support for Docker 17.12.1 and 18.03.1
• Remove support for Docker official support for 17.06
• Change the api method to docker.images.get to docker.images.inspect, this was probably a typo initially because for the docker cli is docker image inspect
• Clean the tests a bit
• Remove aiohttp 2.3 as support version

Are there changes in behavior for the user?

No.

Related issue number

Checklist

• I think the code is well written
• Unit tests for the changes exist
• Documentation reflects the changes
• 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.
• 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]

Codecov Report

Merging #164 into master will increase coverage by 0.07%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #164      +/-   ##
==========================================
+ Coverage   83.73%   83.81%   +0.07%     
==========================================
  Files          19       19              
  Lines         904      908       +4     
==========================================
+ Hits          757      761       +4     
  Misses        147      147

Impacted Files	Coverage Δ
aiodocker/docker.py	80.76% <ø> (ø)	⬆️
aiodocker/images.py	89.65% <100%> (+0.49%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 5b864c1...35f19d8. Read the comment docs.

[barrachri]

Strange error.

aiohttp.client_exceptions.ServerDisconnectedError: None

It seems the docker daemon is closing the connection.

[asvetlov]

Yes.
Looks like we have flaky tests (again)

[barrachri]

I can't replicate the issue with docker api 1.32 locally.......

[barrachri]

Cool, finally ✅.

Happy to drop support for DOCKER 17.09.

[asvetlov]

+1