Use the preferred name for Apple's OS

Co-authored-by: Nicholas McDonnell <[email protected]>

Author: jsf9k

update_molecule_images.sh

@@ -43,6 +43,6 @@ fi
 check_dependencies
 
 # Note that we can't use --max-args in place of -n in the xargs
-# command since the version of xargs distributed with OSX does not
+# command since the version of xargs distributed with macOS does not
 # support it.
 yq '.platforms[].image' < "$source_file" | xargs -n 1 docker pull