feat: enhance Matrix notifier with JSON encoding

Improved the Matrix notifier's message delivery by converting data payloads to JSON format before sending. This change includes encoding the message data as UTF-8 and setting the appropriate `Content-Type` header in the request. This adjustment ensures better compatibility with the Matrix API and potentially reduces issues related to content formatting and data interpretation on the receiving end.

Refactored import statements for clarity and consistency within the module.

src/trackbert/notifiers/matrix.py

@@ -1,8 +1,9 @@
 from typing import Dict, Any
+from urllib.request import Request, urlopen
 
-from urllib.request import urlopen
+import json
 
-from trackbert.classes.notifier import BaseNotifier
+from ..classes.notifier import BaseNotifier
 
 
 class Matrix(BaseNotifier):
@@ -19,6 +20,13 @@ class Matrix(BaseNotifier):
 
         url = f"{homeserver}/_matrix/client/r0/rooms/{room_id}/send/m.room.message?access_token={token}"
 
-        data = {"msgtype": "m.text", "body": f"{title}\n\n{message}"}
+        data = json.dumps(
+            {"msgtype": "m.text", "body": f"{title}\n\n{message}"}
+        ).encode("utf-8")
 
-        urlopen(url, data=data)
+        req = Request(url, data=data, headers={"Content-Type": "application/json"})
+
+        urlopen(req)
+
+
+notifier = Matrix