Stack Push

As you know, our stack has a count and a capacity... but what happens when the count is equal to the capacity? We need to make room for more data!

We'll take a simple approach: whenever we run out of capacity, we'll double it. That way we don't have to reallocate memory on every push. For example:

Complete the stack_push function. It safe(ish)ly adds a new object to the top of the stack. Remember: the size of the data array is the capacity of the stack, and the number of elements that are actually in the stack is the count (which is less than or equal to the capacity).

1. If the stack's count is equal to the stack's capacity:
   1. Double the stack's capacity
   2. Reallocate enough memory for the stack's data using the new capacity (tip below on how to do this)
   3. If realloc fails, set the stack's capacity back and return from the function. The old data is still valid.
   4. If it succeeds, update the stack's data field to point to the new memory
2. Add the new object to the top of the stack (the count-th element in the array)
3. Increment the stack's count

The realloc function is used to resize memory that was previously allocated with malloc or calloc. It takes a pointer to the old memory and the new size, and returns a pointer to the new memory:

void *realloc(void *ptr, size_t size);

int *smol_boi = malloc(10 * sizeof(int));
int *large_boi = realloc(smol_boi, 20 * sizeof(int));