mathlib3

299984b4 - feat(combinatorics/simple_graph/uniform): Graph uniformity and uniform partitions (#12957)

feat(combinatorics/simple_graph/uniform): Graph uniformity and uniform partitions (#12957) Define uniformity of a pair of vertices in a graph and uniformity of a partition of vertices of a graph. Co-authored-by: Bhavik Mehta <bhavik.mehta8@gmail.com>