fix: add <cstdint> to count_bit_flips.cpp

bit_manipulation/count_bits_flip.cpp

@@ -20,6 +20,7 @@
  * @author [Yash Raj Singh](https://github.com/yashrajyash)
  */
 #include <cassert>   /// for assert
+#include <cstdint>   /// for integral typedefs
 #include <iostream>  /// for IO operations
 /**
  * @namespace bit_manipulation