Align ebfmi threshold with cmdstan

[andrjohns]

Submission Checklist

• Run unit tests
• Declare copyright holder and agree to license (see below)

Summary

The cmdstanr diagnostic threshold for low E-BFMI is 0.2, while the cmdstan threshold is 0.3

Copyright and Licensing

Please list the copyright holder for the work you are submitting
(this will be you or your assignee, such as a university or company):
Andrew Johnson

By submitting this pull request, the copyright holder is agreeing to
license the submitted work under the following licenses:

• Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
• Documentation: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (48a2b3e) 88.36% compared to head (6b40704) 88.36%.

❗ Current head 6b40704 differs from pull request most recent head 29a4682. Consider uploading reports for the commit 29a4682 to get more accurate results

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #892   +/-   ##
=======================================
  Coverage   88.36%   88.36%           
=======================================
  Files          12       12           
  Lines        4528     4528           
=======================================
  Hits         4001     4001           
  Misses        527      527           

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[andrjohns]

Going to merge this since it's minor and should be considered a bugfix