Do not test exact serial number because its changes for every renewal

Author: fabricereix

integration/ssl/letsencrypt.hurl

@@ -4,4 +4,4 @@ HTTP 200
 certificate "Subject" == "CN=hurl.dev"
 certificate "Issuer" == "C=US, O=Let's Encrypt, CN=R3"
 certificate "Expire-Date" daysAfterNow > 15
-certificate "Serial-Number" == "03:db:c4:f3:c8:5e:13:66:cc:52:a3:69:2c:fa:04:a0:7b:b1"
+certificate "Serial-Number" matches "[0-9af]+"