SymPy v2 cannot be loaded in CI with Julia v1.6

[ranocha]

Describe the bug
I observe the following error in CI:

ERROR: LoadError: InitError: ArgumentError: ref of NULL PyObject
Stacktrace:
  [1] _getproperty(o::PyCall.PyObject, s::Symbol)
    @ PyCall ~/.julia/packages/PyCall/KLzIO/src/PyCall.jl:299
  [2] __getproperty
    @ ~/.julia/packages/PyCall/KLzIO/src/PyCall.jl:312 [inlined]
  [3] getproperty(o::PyCall.PyObject, s::Symbol)
    @ PyCall ~/.julia/packages/PyCall/KLzIO/src/PyCall.jl:318
  [4] __init__()
    @ SymPy ~/.julia/packages/SymPyCore/EgrjB/src/SymPy/sympy.jl:123
  [5] _include_from_serialized(path::String, depmods::Vector{Any})
    @ Base ./loading.jl:696
  [6] _require_search_from_serialized(pkg::Base.PkgId, sourcepath::String)
    @ Base ./loading.jl:782
  [7] _require(pkg::Base.PkgId)
    @ Base ./loading.jl:1020
  [8] require(uuidkey::Base.PkgId)
    @ Base ./loading.jl:936
  [9] require(into::Module, mod::Symbol)
    @ Base ./loading.jl:923
 [10] include(fname::String)
    @ Base.MainInclude ./client.jl:444
 [11] top-level scope
    @ none:6
during initialization of module SymPy

See https://github.com/ranocha/BSeries.jl/actions/runs/6978438964/job/18989851345?pr=180#step:7:213

To Reproduce
Run CI with SymPy.jl v2

Expected behavior
It can be loaded and doesn't throw an error.

[jverzani]

Thanks,

There was an issue with PyCall before I tagged 2.0, but I assumed this was a transient issue, as has happened in the past. Looks like no such luck. I'd suggest holding off from bumping your compat bound until I can sort this out.

[jverzani]

I'm flying a bit blind, but #540 and the resulting tag should address this. Thanks.