Update conferences

Author: oleksis

_data/conferences.yml

@@ -1,7 +1,8 @@
 - dates: 16 Dec - 17 Dec 2023
   location: _No response_
   name: FlaskCon 2023
-  speaking: '* Jay Miller - End-to-End Flask App Testing with Playwright'
+  speaking: "* Jay Miller - End-to-End Flask App Testing with Playwright\r\n* Brayan\
+    \ Mwanyumba - Building a Scalable Machine Learning API with Flask and TensorFlow"
   summary: _No response_
   type: online
   url: https://flaskcon.com/2023/