Update Comparison tests to Catlab > v0.16.9

Comparison tests in `test/ModelComparison.jl` pass on Catlab v0.16.9 but fail on later versions.

I am not sure what the intention of these tests is, but note that by changing line 32 in `test/ModelComparison.jl` from
```julia
so = Subobject.(legs(c_res))
```
to
```julia
so = Subobject.(feet(c_res))
```
, all following logical tests pass save for:
```julia
¬(A ∧ B) != ¬(A) ∨ B
```
and
```julia
implies((A∧B), A) == A∨B
```

Those tests further pass if `==` and `!=` are substituted in respectively.