SyntaxWarning: "is not" with a literal. Did you mean "!="?

[merkys]

The following line:

pycifrw/src/CifFile_module.nw

Line 561 in bd9b7ae

if do_imports is not 'No':

emits a SyntaxWarning on Python 3.11:

CifFile/CifFile_module.py:356
  CifFile/CifFile_module.py:356: SyntaxWarning: "is not" with a literal. Did you mean "!="?
    if do_imports is not 'No':

[jamesrhester]

Yes, it should be '!='