chore: remove stray line break (leanprover-community#40719)

Author: eric-wieser

Mathlib/GroupTheory/Congruence/Hom.lean

@@ -40,7 +40,6 @@ namespace Con
 section Mul
 variable {F} [Mul M] [Mul N] [Mul P] [FunLike F M N] [MulHomClass F M N]
 
-
 /-- The natural homomorphism from a magma to its quotient by a congruence relation. -/
 @[to_additive (attr := simps) /-- The natural homomorphism from an additive magma to its quotient by
 an additive congruence relation. -/]