Attempt #2: Update gyb to latest version and use python3

Shared/Secrets.swift.gyb

@@ -8,14 +8,14 @@ def chunks(seq, size):
   return (seq[i:(i + size)] for i in range(0, len(seq), size))
 
 def encode(string, salt):
-  bytes = string.encode("UTF-8")
-  return [ord(bytes[i]) ^ salt[i % len(salt)] for i in range(0, len(bytes))]
+  bytes_ = string.encode("UTF-8")
+  return [bytes_[i] ^ salt[i % len(salt)] for i in range(0, len(bytes_))]
 
 def snake_to_camel(snake_str):
   components = snake_str.split('_')
   return components[0].lower() + ''.join(x.title() for x in components[1:])
 
-salt = [ord(byte) for byte in os.urandom(64)]
+salt = [byte for byte in os.urandom(64)]
 }%
 import Secrets