build: Require python 3.5

test/functional/test_framework/script.py

@@ -449,10 +449,6 @@ class CScript(bytes):
         # join makes no sense for a CScript()
         raise NotImplementedError
 
-    # Python 3.4 compatibility
-    def hex(self):
-        return self.hex()
-
     def __new__(cls, value=b''):
         if isinstance(value, bytes) or isinstance(value, bytearray):
             return super(CScript, cls).__new__(cls, value)