vici: Explicitly set the Python encoding type

When using vici over RPyC and its (awesome) splitbrain, encoding and decoding
strings fails in vici, most likely because of the Monkey-Patch magic splitbrain
uses.

When specifying the implicit UTF-8 as encoding scheme explicitly, Python uses
the correct method to encode/decode the string, making vici useable in
splitbrain contexts.

src/libcharon/plugins/vici/python/vici/protocol.py

@@ -62,7 +62,7 @@ class Packet(object):
 
     @classmethod
     def _named_request(cls, request_type, request, message=None):
-        request = request.encode()
+        requestdata = request.encode("UTF-8")
         payload = struct.pack("!BB", request_type, len(request)) + request
         if message is not None:
             return payload + message
@@ -105,12 +105,12 @@ class Message(object):
     @classmethod
     def serialize(cls, message):
         def encode_named_type(marker, name):
-            name = name.encode()
+            name = name.encode("UTF-8")
             return struct.pack("!BB", marker, len(name)) + name
 
         def encode_blob(value):
             if not isinstance(value, bytes):
-                value = str(value).encode()
+                value = str(value).encode("UTF-8")
             return struct.pack("!H", len(value)) + value
 
         def serialize_list(lst):
@@ -147,7 +147,7 @@ class Message(object):
     def deserialize(cls, stream):
         def decode_named_type(stream):
             length, = struct.unpack("!B", stream.read(1))
-            return stream.read(length).decode()
+            return stream.read(length).decode("UTF-8")
 
         def decode_blob(stream):
             length, = struct.unpack("!H", stream.read(2))