Remove redundant TimeoutError class

[farahats9]

What do these changes do?

Remove the builtins.TimeoutError class from base classes of aioredis.exceptions.TimeoutError because it is causing an error due to its redundancy.

Are there changes in behavior for the user?

No

Related issue number

#1443

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> (e.g. 588.bugfix)
  • 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.

[lgtm-com]

This pull request introduces 1 alert when merging 3ad900b into 19be499 - view on LGTM.com

new alerts:

• 1 for Unused import

[Rooba]

considering __builtins__ is already going to be present, the import for builtins poses no difference.