Core/Database: Remove future/promise typedefs from a public header (these are internal to database project)

src/server/database/Database/MySQLConnection.h

@@ -24,6 +24,7 @@
 #include <memory>
 #include <mutex>
 #include <string>
+#include <thread>
 #include <vector>
 
 class MySQLPreparedStatement;