warkaround for gcc 7.2.0: make modernjson compile again

resources/3rdparty/modernjson/src/json.hpp

@@ -5650,7 +5650,8 @@ Format](http://rfc7159.net/rfc7159)
                 {
                     case value_t::array:
                     {
-                        return *lhs.m_value.array < *rhs.m_value.array;
+                        // Workaround for gcc 7.2.0, which parses array< as a template.
+                        return (*lhs.m_value.array) < *rhs.m_value.array;
                     }
                     case value_t::object:
                     {

src/storm/storage/jani/JSONExporter.h

@@ -9,7 +9,7 @@
 // JSON parser
 #include "json.hpp"
 namespace modernjson {
-    using json = nlohmann::basic_json<std::map, std::vector, std::string, bool, int64_t, uint64_t, double, std::allocator>;
+    using json = nlohmann::json;
 }
 
 namespace storm {