Test failures in h5a_iterate

[simonbyrne]

Something really odd is going on with the CI / julia 1 - windows-latest - x64.

We're getting an error in h5a_iterate:
https://github.com/JuliaIO/HDF5.jl/actions/runs/6124333998/job/16624132842#step:5:200
From what I can tell, it looks like h5a_iterate isn't throwing an error correctly. I can make it go away by removing the lock or the try/catch for the lock, or be removing the check of the error stack (which may be a good idea in any case?)

Originally posted by @simonbyrne in #1104 (comment)

[simonbyrne]

Similar error on Ubuntu with Julia 1.6:
https://github.com/JuliaIO/HDF5.jl/actions/runs/6125740497/job/16628314924#step:5:1