create-pull-request: increase likelihood of detecting a rename

Decrease the similarity percentage needed to recognize a delete/add-pair followed by an edit,
as a rename.
This make reviewing patches easier.

(From OE-Core rev: 3944f5e02d22b70b3bcd733a80f005dbd8e248a2)

Signed-off-by: Anders Darander <anders@chargestorm.se>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/create-pull-request

@@ -166,7 +166,7 @@ mkdir $ODIR
 
 
 # Generate the patches and cover letter
-git format-patch -M --subject-prefix="$PREFIX" -n -o $ODIR --thread=shallow --cover-letter $RELATIVE_TO..$COMMIT_ID > /dev/null
+git format-patch -M40 --subject-prefix="$PREFIX" -n -o $ODIR --thread=shallow --cover-letter $RELATIVE_TO..$COMMIT_ID > /dev/null
 
 
 # Customize the cover letter