Fix websocket watchdog not canceling when websocket disconnects

[bachya]

Describe what the PR does:

The websocket watchdog wasn't properly canceling when we disconnected from the websocket. This could create an unnecessary loop of the watchdog triggering. This PR fixes things.

Does this fix a specific issue?

N/A

Checklist:

• Confirm that one or more new tests are written for the new functionality.
• Run tests and ensure everything passes (with 100% test coverage).
• Update README.md and docs/ with any new documentation.
• Add yourself to AUTHORS.md.

[qlty-cloud-legacy]

Code Climate has analyzed commit 4e6e167 and detected 0 issues on this pull request.

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[codecov]

Codecov Report

Merging #293 (4e6e167) into dev (833be42) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##              dev     #293   +/-   ##
=======================================
  Coverage   99.77%   99.77%           
=======================================
  Files          13       13           
  Lines         903      903           
=======================================
  Hits          901      901           
  Misses          2        2           

Impacted Files	Coverage Δ
simplipy/websocket.py	100.00% <100.00%> (ø)

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