conglatt: fix ordering issue

[james-d-mitchell]

This PR fixes an issue relating to the ordering of congruences in CongruencesOfSemigroup and in the nodes of the associated LatticeOfCongruences, before this change (and after v4.0.0) they didn't agree:

gap> S := InverseSemigroup(PartialPerm([1, 3], [2, 4]),
>                          PartialPerm([1], [1]));;
gap> D := DigraphReflexiveTransitiveReduction(LatticeOfRightCongruences(S));
<immutable digraph with 22 vertices, 49 edges>
gap> S := InverseSemigroup(PartialPerm([1, 3], [2, 4]),
>                          PartialPerm([1], [1]));;
gap> D := DigraphReflexiveTransitiveReduction(LatticeOfRightCongruences(S));
<immutable digraph with 22 vertices, 49 edges>
gap> x := DigraphSinks(D)[1];
2
gap> NrEquivalenceClasses(RightCongruencesOfSemigroup(S)[x]);
7

when the correct value should be 1 (for the universal congruence).

[james-d-mitchell]

Hopefully the CI failing is a transient issue ....