Fix check_url function.

templates/event-generator/prepare_experiment.sh

@@ -33,7 +33,7 @@ function check_url() {
   # Check if the url exists
   local url="$1"
   status=$(
-    (curl -s --head $url | head -n 1 | grep "HTTP/2 200 " >/dev/null)
+    (curl -s --head $url | head -n 1 | grep  "HTTP/1.[01] [23].." >/dev/null)
     echo $?
   )
   if [ $status -eq 0 ]; then