Fix scikit-image deprecation warning

[psavery]

Describe the bug

As described below:

/home/patrick/virtualenvs/hexrd/src/hexrd/hexrd/core/instrument/hedm_instrument.py:1839: FutureWarning: `RegionProperties.weighted_centroid` is deprecated starting in version 0.26 and will be removed in version 2.0. Use `RegionProperties.centroid_weighted` instead. 

Impact

Will eventually cause someone a problem

Reproduction

Run fit-grains with the latest scikit-image

Version

Affected Workflows

• core
• EDD
• HEDM
• Powder
• Laue