Use sphinx lower than version 7

brandonwillard · brandonwillard · commit 4b2fc4217bde · 2023-09-20T17:20:45.000-05:00
diff --git a/doc/environment.yml b/doc/environment.yml
@@ -9,7 +9,7 @@ dependencies:
   - numpy
   - scipy
   - six
-  - sphinx>=3
+  - sphinx>=3,<7
   - sphinx-book-theme
   - sphinx-design
   - sphinx_rtd_theme
