Tests fail on Python 3.8 and 3.9

[FuzzyGophers]

ctypesgen builds fine on py3.8 and py3.9, but the tests fail:

OK

• python3_8: running distutils-r1_run_phase python_test
  ....................................../var/tmp/portage/dev-python/ctypesgen-1.0.2/work/ctypesgen-ctypesgen-1.0.2/ctypesgen/test/../../temp.py:2861: SyntaxWarning: 'NoneType' object is not callable; perhaps you missed a comma?
  return (None (ord_if_char((((__FDS_BITS (set)) [(__FD_ELT (d))]) | (__FD_MASK (d)))))).value
  /var/tmp/portage/dev-python/ctypesgen-1.0.2/work/ctypesgen-ctypesgen-1.0.2/ctypesgen/test/../../temp.py:2865: SyntaxWarning: 'NoneType' object is not callable; perhaps you missed a comma?
  return (None (ord_if_char((((__FDS_BITS (set)) [(__FD_ELT (d))]) & ((__FD_MASK (d))))))).value
  ./var/tmp/portage/dev-python/ctypesgen-1.0.2/work/ctypesgen-ctypesgen-1.0.2/ctypesgen/test/../../temp.py:2861: SyntaxWarning: 'NoneType' object is not callable; perhaps you missed a comma?
  return (None (ord_if_char((((__FDS_BITS (set)) [(__FD_ELT (d))]) | (__FD_MASK (d)))))).value
  /var/tmp/portage/dev-python/ctypesgen-1.0.2/work/ctypesgen-ctypesgen-1.0.2/ctypesgen/test/../../temp.py:2865: SyntaxWarning: 'NoneType' object is not callable; perhaps you missed a comma?
  return (None (ord_if_char((((__FDS_BITS (set)) [(__FD_ELT (d))]) & ((__FD_MASK (d))))))).value
  .......

---

Ran 46 tests in 7.567s

[same for 3.9]

[Alan-R]

The version in source control currently passes tests on 2.7, 3.7, 3.8 and 3.9. Please check that version and reopen this if it is still failing for you.