AlarmServer: fix crash on Python 3.9+ (json.loads encoding kwarg)

The `encoding` keyword argument to `json.loads` was deprecated in
Python 3.1 and removed in 3.9, so `AlarmServer.py` has been crashing on
the very first received packet under any modern Python install:

    TypeError: JSONDecoder.__init__() got an unexpected keyword argument 'encoding'

Decode the bytes once and strip the framing tail (`\x00\n`) before
handing the string to `json.loads`. Verified with a self-test packet on
Python 3.13.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

AlarmServer.py

@@ -40,7 +40,7 @@ while True:
         sleep(0.1)  # Just for recive whole packet
         data = conn.recv(len_data)
         conn.close()
-        reply = json.loads(data, encoding="utf8")
+        reply = json.loads(data.decode("utf-8", errors="replace").rstrip("\x00\n"))
         print(datetime.now().strftime("[%Y-%m-%d %H:%M:%S]>>>"))
         print(head, version, session, sequence_number, msgid, len_data)
         print(json.dumps(reply, indent=4, sort_keys=True))