C++ RedBlack Tree: duplicate check in 'FixDelete' function: 's->right->color ==0'

[NiekBeijloos]

https://github.com/Bibeknam/algorithmtutorprograms/blob/bbbc4ff16b15a2fd50308c996e236d124a024b85/data-structures/red-black-trees/RedBlackTree.cpp#L115C56-L115C56