Bump version to 1.21

Author: stefankoegl

jsonpatch.py

@@ -58,7 +58,7 @@
 
 # Will be parsed by setup.py to determine package metadata
 __author__ = 'Stefan Kögl <[email protected]>'
-__version__ = '1.20'
+__version__ = '1.21'
 __website__ = 'https://github.com/stefankoegl/python-json-patch'
 __license__ = 'Modified BSD License'