[3.12] Fix doctrees directory for the gettext builder (pythonGH-122997) (python#124339)

Fix doctrees directory for the gettext builder (pythonGH-122997)
(cherry picked from commit 315a933)

Co-authored-by: Rafael Fontenelle <[email protected]>

Author: miss-islington

Doc/Makefile

@@ -144,7 +144,7 @@ pydoc-topics: build
 
 .PHONY: gettext
 gettext: BUILDER = gettext
-gettext: SPHINXOPTS += '-d build/doctrees-gettext'
+gettext: SPHINXOPTS += -d build/doctrees-gettext
 gettext: build
 
 .PHONY: htmlview