az.to_netcdf errors in variables containing / in names

[ferrine]

Description of your problem

in #5607 variable scopes became separated by / which appeared to be an incompatibility with HDF5 format. No longer these models save with az.to_netcdf

We need a different semantic separator for scopes that is compliant with hdf5 saving

Versions and main components

• PyMC/PyMC3 Version: '4.0.0b5'
• Aesara/Theano Version: not ralated
• Python Version: not ralated
• Operating system: Linux
• How did you install PyMC/PyMC3: (conda/pip) conda

[ricardoV94]

Vertical pipe |?

... Until we find another backend that fails with those xD

[ferrine]

I'm on the PR, changing to |