py3.10 c++ issue

[dragonyanglong]

error:

SystemError: PY_SSIZE_T_CLEAN macro must be defined for '#' formats

possible solution:
"* "The PY_SSIZE_T_CLEAN macro must now be defined to use PyArg_ParseTuple() and Py_BuildValue() formats which use #: es#, et#, s#, u#, y#, z#, U# and Z#. See Parsing arguments and building values and the PEP 353."

[dragonyanglong]

this error should be fixed in pdffit2 package, not related with pdfgui. link with this issue (diffpy/diffpy.pdffit2#14)

[bobleesj]

We can close this since it's a pdffit2 problem and has been resolved in the PR linked above.

[bobleesj]

@sbillinge Could you please close this? The issue above by @dragonyanglong has been fixed with a PR.

[sbillinge]

closed in the same PR as #103