define unicode for Py3

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@74352 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/python/temporal/temporal_algebra.py

@@ -447,6 +447,7 @@ except:
     pass
 
 import os
+import sys
 import copy
 from datetime import datetime
 import grass.pygrass.modules as pymod
@@ -469,6 +470,9 @@ from .datetime_math import create_suffix_from_datetime
 from .datetime_math import create_time_suffix
 from .datetime_math import create_numeric_suffix
 
+if sys.version_info[0]:
+    unicode = str
+
 ##############################################################################
 
 class TemporalAlgebraLexer(object):