Update template

Author: sachaos

templates/c++/main.cpp

@@ -1,8 +1,8 @@
 // Code for {{.Task.Name}}
-#include <iostream>
+#include <bits/stdc++.h>
 using namespace std;
 
 int main() {
 	cout << "Hello world" << endl;
 	return 0;
-}
+}