make Sympy version detection 2.0-ready

pystencils/data_types.py

@@ -583,7 +583,7 @@ def get_type_of_expression(expr,
 
 
 sympy_version = sp.__version__.split('.')
-if int(sympy_version[0]) <= 1 and int(sympy_version[1]) >= 9:
+if int(sympy_version[0]) * 100 + int(sympy_version[1]) >= 109:
     # __setstate__ would bypass the contructor, so we remove it
     sp.Number.__getstate__ = sp.Basic.__getstate__
     del sp.Basic.__getstate__