add function stack_push

just like the tittle. Thanks for the review. ;D

stack.c

@@ -18,11 +18,6 @@ void stack_destroy(stack *s) {
 
 void stack_push(stack *s, int value)
 {
-    if (s->top == s->capacity-1)
-    {
-        assert(s->data = realloc(s->capacity * 2 * sizeof(int)) && "Error : realloc failed");
-    }
-    
     s->top++;
     s->data[s->top] = value;
 }