Fix Redfish validator warning

Trailing slash warnings now show up in the validator report, so
fix this one.

Tested:
Passed the Redfish Service Validator.

Change-Id: I8db7eb488b44eba9510ae4e1071b2da15eaa22c1
Signed-off-by: Jason M. Bills <jason.m.bills@linux.intel.com>
diff --git a/redfish-core/lib/network_protocol.hpp b/redfish-core/lib/network_protocol.hpp
index 75d13d4..0db1aa2 100644
--- a/redfish-core/lib/network_protocol.hpp
+++ b/redfish-core/lib/network_protocol.hpp
@@ -263,7 +263,7 @@
                 }
                 asyncResp->res.jsonValue["HTTPS"]["Certificates"] = {
                     {"@odata.id", "/redfish/v1/Managers/bmc/NetworkProtocol/"
-                                  "HTTPS/Certificates/"}};
+                                  "HTTPS/Certificates"}};
 
                 for (auto& unit : r)
                 {