docs: Fix a few typos

[timgates42]

There are small typos in:

• doc/topics/models/composite_fields.rst
• flywheel/engine.py
• setup.py
• tests/test_models.py

Fixes:

• Should read updates rather than updateds.
• Should read possibility rather than possiblity.
• Should read highlighting rather than highighting.
• Should read constraint rather than contraint.

Semi-automated pull request generated by https://github.com/timgates42/meticulous/blob/master/docs/NOTE.md

[stevearc]

sure seems fine