Fix import in docs for filters.Not

[sighol]

Description

The Not filter had imports for Or and Equals in the docs, when it should have Not and `Equals.

Since this is just docs, I don't think we need a new version of the SDK. The public docs should be re-built when this PR is merged.

Checklist:

• Tests added/updated.
• Documentation updated. Documentation is generated from docstrings - these must be updated according to your change.
  If a new method has been added it should be referenced in cognite.rst in order to generate docs based on its docstring.
• Changelog updated in CHANGELOG.md.
• Version bumped. If triggering a new release is desired, bump the version number in _version.py and pyproject.toml per semantic versioning.

[codecov]

Codecov Report

Merging #1535 (7825382) into master (6ec2c15) will decrease coverage by 0.01%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1535      +/-   ##
==========================================
- Coverage   91.75%   91.75%   -0.01%     
==========================================
  Files         120      120              
  Lines       15591    15591              
==========================================
- Hits        14306    14305       -1     
- Misses       1285     1286       +1     

Files	Coverage Δ
cognite/client/data_classes/filters.py	98.07% <ø> (ø)

... and 1 file with indirect coverage changes

[haakonvt]

How was this not picked up by the doctests?!