Delete .bak file produced during publish

extras/scripts/build-single-header.sh

@@ -55,6 +55,7 @@ process()
 
 simplify_namespaces() {
 	perl -p0i -e 's|\}  // namespace ARDUINOJSON_NAMESPACE\r?\nnamespace ARDUINOJSON_NAMESPACE \{\r?\n||igs' "$1"
+	rm -f "$1.bak"
 }
 
 cd $(dirname $0)/../..