doc: fix build env

updated the requirements

Signed-off-by: Anna Wojdylo <anna.wojdylo@nordicsemi.no>

Author: annwoj

doc/requirements.txt

@@ -1,7 +1,4 @@
-# Tested with pythn 3.12.4
-# based on ncs doc requirements
-
-sphinx>=8.1,<8.2
-sphinx-autobuild
-sphinx-ncs-theme
+sphinx>=7.2,<8.2
+sphinx-ncs-theme==0.7.4
 sphinx-tabs>=3.4
+sphinx-copybutton