mathlib3

c06c6169 - feat(number_theory/arithmetic_function): Moebius inversion (#5047)

feat(number_theory/arithmetic_function): Moebius inversion (#5047) Changes the way that zeta works with coercion Proves Möbius inversion for functions to a general `comm_ring` Co-authored-by: jalex-stark <alexmaplegm@gmail.com>