Remove cast to unicode

```
************* Module saml2.saml
src/saml2/saml.py:168:15: E0602: Undefined variable 'unicode' (undefined-variable)
```

There is no compatibility to python2 anymore. We can safely remove any such checks that
tried to set the right types for the string object to catter for the differences in
types between py2 and py3.

Signed-off-by: Ivan Kanakarakis <[email protected]>

Author: c00kiemon5ter

src/saml2/saml.py

@@ -160,17 +160,16 @@ def clear_type(self):
 
     def set_text(self, value, base64encode=False):
         def _wrong_type_value(xsd, value):
-            msg = _str('Type and value do not match: {xsd}:{type}:{value}')
+            msg = 'Type and value do not match: {xsd}:{type}:{value}'
             msg = msg.format(xsd=xsd, type=type(value), value=value)
             raise ValueError(msg)
 
         # only work with six.string_types
-        _str = unicode if six.PY2 else str
         if isinstance(value, six.binary_type):
             value = value.decode('utf-8')
 
         type_to_xsd = {
-            _str:       'string',
+            str:        'string',
             int:        'integer',
             float:      'float',
             bool:       'boolean',
@@ -183,51 +182,51 @@ def _wrong_type_value(xsd, value):
         # - a function to turn that type into a text-value
         xsd_types_props = {
             'string': {
-                'type': _str,
-                'to_type': _str,
-                'to_text': _str,
+                'type': str,
+                'to_type': str,
+                'to_text': str,
             },
             'integer': {
                 'type': int,
                 'to_type': int,
-                'to_text': _str,
+                'to_text': str,
             },
             'short': {
                 'type': int,
                 'to_type': int,
-                'to_text': _str,
+                'to_text': str,
             },
             'int': {
                 'type': int,
                 'to_type': int,
-                'to_text': _str,
+                'to_text': str,
             },
             'long': {
                 'type': int,
                 'to_type': int,
-                'to_text': _str,
+                'to_text': str,
             },
             'float': {
                 'type': float,
                 'to_type': float,
-                'to_text': _str,
+                'to_text': str,
             },
             'double': {
                 'type': float,
                 'to_type': float,
-                'to_text': _str,
+                'to_text': str,
             },
             'boolean': {
                 'type': bool,
                 'to_type': lambda x: {
                     'true': True,
                     'false': False,
-                }[_str(x).lower()],
-                'to_text': lambda x: _str(x).lower(),
+                }[str(x).lower()],
+                'to_text': lambda x: str(x).lower(),
             },
             'base64Binary': {
-                'type': _str,
-                'to_type': _str,
+                'type': str,
+                'to_type': str,
                 'to_text': (
                     lambda x: base64.encodebytes(x.encode()) if base64encode else x
                 ),
@@ -264,7 +263,7 @@ def _wrong_type_value(xsd, value):
         to_text = xsd_type_props.get('to_text', str)
 
         # cast to correct type before type-checking
-        if type(value) is _str and valid_type is not _str:
+        if type(value) is str and valid_type is not str:
             try:
                 value = to_type(value)
             except (TypeError, ValueError, KeyError) as e: