feat: Upgrade sphinx and removed edx-sphinx-theme

requirements/common_constraints.txt

@@ -29,8 +29,3 @@ django-simple-history==3.0.0
 # tox>4.0.0 isn't yet compatible with many tox plugins, causing CI failures in almost all repos.
 # Details can be found in this discussion: https://github.com/tox-dev/tox/discussions/1810
 tox<4.0.0
-
-# edx-sphinx-theme is not compatible with latest Sphinx==6.0.0 version 
-# Pinning Sphinx version unless the compatibility issue gets resolved
-# For details, see issue https://github.com/openedx/edx-sphinx-theme/issues/197
-sphinx<6.0.0

requirements/edx/development.txt

@@ -675,8 +675,6 @@ edx-search==3.5.0
     # via -r requirements/edx/testing.txt
 edx-sga==0.22.0
     # via -r requirements/edx/testing.txt
-edx-sphinx-theme==3.1.0
-    # via -r requirements/edx/development.in
 edx-submissions==3.5.6
     # via
     #   -r requirements/edx/testing.txt
@@ -1547,9 +1545,8 @@ soupsieve==2.4.1
     # via
     #   -r requirements/edx/testing.txt
     #   beautifulsoup4
-sphinx==5.3.0
+sphinx==6.2.1
     # via
-    #   -c requirements/edx/../common_constraints.txt
     #   pydata-sphinx-theme
     #   sphinx-book-theme
     #   sphinxcontrib-httpdomain

requirements/edx/doc.txt

@@ -77,9 +77,8 @@ snowballstemmer==2.2.0
     # via sphinx
 soupsieve==2.4.1
     # via beautifulsoup4
-sphinx==5.3.0
+sphinx==6.2.1
     # via
-    #   -c requirements/edx/../common_constraints.txt
     #   -r requirements/edx/doc.in
     #   pydata-sphinx-theme
     #   sphinx-book-theme