fix: add <cstdint> to numerical_methods/**

numerical_methods/brent_method_extrema.cpp

@@ -16,6 +16,7 @@
 #define _USE_MATH_DEFINES  ///< required for MS Visual C++
 #include <cassert>
 #include <cmath>
+#include <cstdint>  /// for integral typedefs
 #include <functional>
 #include <iostream>
 #include <limits>

numerical_methods/durand_kerner_roots.cpp

@@ -33,6 +33,7 @@
 #include <cassert>
 #include <cmath>
 #include <complex>
+#include <cstdint>  /// for integral typedefs
 #include <cstdlib>
 #include <ctime>
 #include <fstream>

numerical_methods/fast_fourier_transform.cpp

@@ -22,6 +22,7 @@
 #include <cassert>   /// for assert
 #include <cmath>     /// for mathematical-related functions
 #include <complex>   /// for storing points and coefficents
+#include <cstdint>   /// for integral typedefs
 #include <iostream>  /// for IO operations
 #include <vector>    /// for std::vector
 

numerical_methods/golden_search_extrema.cpp

@@ -10,6 +10,7 @@
 #define _USE_MATH_DEFINES  //< required for MS Visual C++
 #include <cassert>
 #include <cmath>
+#include <cstdint>  /// for integral typedefs
 #include <functional>
 #include <iostream>
 #include <limits>

numerical_methods/inverse_fast_fourier_transform.cpp

@@ -14,6 +14,7 @@
 #include <cassert>   /// for assert
 #include <cmath>     /// for mathematical-related functions
 #include <complex>   /// for storing points and coefficents
+#include <cstdint>   /// for integral typedefs
 #include <iostream>  /// for IO operations
 #include <vector>    /// for std::vector
 

numerical_methods/newton_raphson_method.cpp

@@ -13,6 +13,7 @@
  * \see bisection_method.cpp, false_position.cpp
  */
 #include <cmath>
+#include <cstdint>  /// for integral typedefs
 #include <ctime>
 #include <iostream>
 #include <limits>

numerical_methods/rungekutta.cpp

@@ -19,9 +19,9 @@
  * There can be many such equations
  */
 #include <cassert>   /// asserting the test functions
+#include <cstdint>   /// for integral typedefs
 #include <iostream>  /// for io operations
 #include <vector>    /// for using the vector container
-
 /**
  * @brief The change() function is used
  * to return the updated iterative value corresponding