Remove pillow version requirement

[Darylgolden]

Changelog / Overview

Motivation

#1740 fixed pillow to <8.3.0 because of python-pillow/Pillow#5571. Now that it's fixed, this requirement can be removed. Fixes #1814.

Explanation for Changes

Documentation Reference

Testing Status

Further Comments

Checklist

• I have read the Contributing Guidelines
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Reviewer Checklist

• The PR title is descriptive enough
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• The changelog entry is completed if necessary
• Newly added functions/classes either have a docstring or are private
• Newly added functions/classes have tests added and (optional) examples in the docs
• Newly added documentation builds, looks correctly formatted, and adds no additional build warnings