Use nlohmann::json::object_t for dump entries

This is a similar change that was recently made for other entry types,
so also applying for dump entries.

I don't have a system that uses this resource, so I'm not able to test
this change.

Change-Id: I74ba2f05658c6c53d7e397e03aad31a44c7c3280
Signed-off-by: Jason M. Bills <jason.m.bills@intel.com>
diff --git a/redfish-core/lib/log_services.hpp b/redfish-core/lib/log_services.hpp
index c118deb..ffae14d 100644
--- a/redfish-core/lib/log_services.hpp
+++ b/redfish-core/lib/log_services.hpp
@@ -407,7 +407,7 @@
             uint64_t timestamp = 0;
             uint64_t size = 0;
             std::string dumpStatus;
-            nlohmann::json thisEntry;
+            nlohmann::json::object_t thisEntry;
 
             std::string entryID = object.first.filename();
             if (entryID.empty())