Update usability score thresholds

[pmachapman]

These are the updated values from silnlp.

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This change is 

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.30%. Comparing base (7835067) to head (ab01fc7).

Additional details and impacted files

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  Coverage   73.30%   73.30%           
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  Files         443      443           
  Lines       37203    37203           
  Branches     5110     5110           
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  Hits        27272    27272           
  Misses       8805     8805           
  Partials     1126     1126           

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[ddaspit]

@ddaspit reviewed 2 files and all commit messages, and made 1 comment.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on Enkidu93 and pmachapman).

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src/SIL.Machine/QualityEstimation/ChrF3QualityEstimator.cs line 35 at r1 (raw file):

        /// The threshold values used to calculate the usability label for every book or text.
        /// </summary>
        public Thresholds BookThresholds { get; set; } = new Thresholds(greenThreshold: 0.776, yellowThreshold: 0.681);

These values should be constants.

[Enkidu93]

Will any of the changes here need to be ported as well? Are there plans for silnlp to move to using machine.py for this soon so it's easier to keep the code in sync?

@Enkidu93 reviewed 2 files and all commit messages, and made 1 comment.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on pmachapman).