bump sphinx so it works on Python3.10 (#2546)

MarcoGorelli · JelleZijlstra · commit e50a04a4f43b · 2021-11-15T18:53:04.000-08:00
diff --git a/docs/requirements.txt b/docs/requirements.txt
@@ -1,6 +1,6 @@
 # Used by ReadTheDocs; pinned requirements for stability.
 
 myst-parser==0.15.1
-Sphinx==4.1.2
+Sphinx==4.2.0
 sphinxcontrib-programoutput==0.17
 sphinx_copybutton==0.4.0
