Tiny improvement to #264

[segasai]

Avoid pinvh() as we already have the eigen decomposition. Add comments

[coveralls]

Pull Request Test Coverage Report for Build 879764370

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.06%) to 71.886%

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Files with Coverage Reduction	New Missed Lines	%
py/dynesty/bounding.py	2	77.04%
<!--	Total:	2		-->

Totals
Change from base Build 879280906:	0.06%
Covered Lines:	3388
Relevant Lines:	4713

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💛 - Coveralls