Bump to Sphinx 4.2 and above

pradyunsg · pradyunsg · commit 4144d6a7f98f · 2021-10-22T08:04:57.000+01:00
This should allow newer versions of Sphinx, which contain bugfixes for
Python 3.10 support.
diff --git a/docs/requirements.txt b/docs/requirements.txt
@@ -1,4 +1,4 @@
-sphinx ~= 4.1.0
+sphinx ~= 4.2
 towncrier
 furo
 myst_parser
