DOC Fix code syntax highlighting accessibility errors (scikit-learn#34376)

Author: DeaMariaLeon

doc/conf.py

@@ -257,7 +257,7 @@
     # check_switcher may be set to False if docbuild pipeline fails. See
     # https://pydata-sphinx-theme.readthedocs.io/en/stable/user_guide/version-dropdown.html#configure-switcher-json-url
     "check_switcher": True,
-    "pygments_light_style": "tango",
+    "pygments_light_style": "sas",
     "pygments_dark_style": "monokai",
     "logo": {
         "alt_text": "scikit-learn homepage",

doc/scss/custom.scss

@@ -8,6 +8,11 @@
 
 /* Global */
 
+/* Needed to override the pydata sphinx theme's default */
+html[data-theme="light"] .highlight pre {
+  background: #fff;
+}
+
 code.literal {
   border: 0;
 }