update .readthedocs.yml. Fixes #591

[cdeline]

• Code changes are covered by tests
• Code changes have been evaluated for compatibility/integration with GUI
• New functions added to __init__.py
• manualapi.rst is up to date, along with other sphinx docs pages
• Example notebooks are rerun and differences in results scrutinized
• Updated changelog

[coveralls]

Pull Request Test Coverage Report for Build 23918007760

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 74.703%

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Totals
Change from base Build 21255981476:	0.0%
Covered Lines:	3904
Relevant Lines:	5226

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💛 - Coveralls

[cdeline]

readthedocs are working.