`gens` is broken for the Gröbner basis cashed for quotient ideals

Describe the bug

Julia complains with a conversion error when one tries to call gens(I.gb) where I is of type MPolyQuoIdeal. I am looking into it.

To Reproduce

One more or less arbitrary example is

using Oscar
R, (x, y, z) = graded_polynomial_ring(QQ, ["x", "y", "z"]);
A, p = quo(R, ideal(R, [x-y]));
V = [x, z^2, x^3+y^3, y^4, y*z^5];
a = ideal(A, V);
dim(a); # this cashes a Gröbner basis
gens(a.gb)

System

julia> Oscar.versioninfo(full=true)
OSCAR version 0.12.1-DEV - #master, e67cca887a -- 2023-04-19 00:42:29 +0200
  combining:
    AbstractAlgebra.jl   v0.29.4
    GAP.jl               v0.9.4
    Hecke.jl             v0.18.9
    Nemo.jl              v0.33.7
    Polymake.jl          v0.9.0
    Singular.jl          v0.18.2
  building on:
    Antic_jll               v0.201.500+0
    Arb_jll                 v200.2300.0+0
    Calcium_jll             v0.401.100+0
    FLINT_jll               v200.900.5+0
    GAP_jll                 v400.1200.200+0
    Singular_jll            v403.201.1+0
    libpolymake_julia_jll   v0.9.0+0
    libsingular_julia_jll   v0.30.0+0
    polymake_jll            v400.900.0+0
...

oscar-system / Oscar.jl

`gens` is broken for the Gröbner basis cashed for quotient ideals #2292