Tests: Remove unused include

Author: https://github.com/BenWiederhake
Commit: https://github.com/SerenityOS/serenity/commit/417ca7594b3
Pull-request: https://github.com/SerenityOS/serenity/pull/3275
Reviewed-by: https://github.com/awesomekling

Userland/Tests/LibC/snprintf-correctness.cpp

@@ -30,9 +30,7 @@
 #include <AK/Random.h>
 #include <AK/StringBuilder.h>
 #include <ctype.h>
-#include <memory.h>
 #include <stdio.h>
-#include <string.h>
 
 struct Testcase {
     const char* dest;