Use sphinx-autoapi 1.8.1 until it's fixed

Related to readthedocs/sphinx-autoapi#299

Author: tannewt

requirements-dev.txt

@@ -16,7 +16,7 @@ cpp-coveralls
 Sphinx<4
 sphinx-rtd-theme
 myst-parser
-sphinx-autoapi
+sphinx-autoapi<=1.8.1
 sphinxcontrib-svg2pdfconverter
 readthedocs-sphinx-search