Fix --only-binary flag

Signed-off-by: Filipe Laíns <[email protected]>

Author: FFY00

Doc/requirements-no-build.txt

@@ -3,7 +3,5 @@
 # Requirements when not running the build Python,
 # such as optional native extensions.
 
---only-binary
-
 # Needed to support generating social cards in sphinxext-opengraph.
-matplotlib
+--only-binary matplotlib