Pin mistune to fix doc builds on RTD.

dihm · dihm · commit 999107da840c · 2022-02-02T17:16:29.000-05:00
diff --git a/setup.cfg b/setup.cfg
@@ -49,3 +49,4 @@ docs =
   sphinx-rtd-theme==0.5.2
   recommonmark==0.6.0
   m2r==0.2.1
+  mistune<2.0.0
