Upgrade docs dependency Sphinx because tests fail

cclauss · ionelmc · commit a7c5c1a57566 · 2024-03-17T15:36:34.000+02:00
https://github.com/pytest-dev/pytest-cov/actions/runs/8193686290/job/22407988436 demonstrates the current test failures.
diff --git a/docs/requirements.txt b/docs/requirements.txt
@@ -1,4 +1,4 @@
-sphinx==3.0.3
+sphinx==7.2.6
 sphinx-py3doc-enhanced-theme==2.4.0
 docutils==0.16
 jinja2<3.1
