bump up sphinx package requirements for readthedocs

Author: glesur

doc/python_requirements.txt

@@ -6,12 +6,12 @@
 # python -m pip install -r python_requirements.txt
 
 wheel>=0.38.4 # help forward compatibility for pip with old sphinx plugins
-sphinx==5.3.0
-sphinx_rtd_theme==1.3.0
+sphinx==9.1.0
+sphinx_rtd_theme==3.1.0
 sphinx_git==11.0.0
-breathe==4.34.0
+breathe==4.36.0
 exhale==0.3.7
-m2r2==0.3.2
+m2r2==0.3.4
 sphinx-copybutton==0.5.2
 #sphinxcontrib-applehelp==1.0.7
 matplotlib==3.10.0