upgrade to Sphinx 9.1.0 release (#1057)

Author: jmckenna

requirements.txt

@@ -1,7 +1,7 @@
 alabaster==1.0.0
-docutils==0.22.3
-sphinx==9.0.4
+docutils==0.22.4
+sphinx==9.1.0
 sphinx-copybutton==0.5.2
 sphinxcontrib-jquery==4.1
 --extra-index-url https://test.pypi.org/simple/
-mapscript==8.4.0
+mapscript==8.6.0