Fix import in codec_usage.py example

- Updated import to use `from compas_eve.codecs import JsonMessageCodec`
- This reflects the change where JsonMessageCodec is no longer exported at top level

Co-authored-by: gonzalocasas <[email protected]>

Author: Copilot

examples/codec_usage.py

@@ -10,7 +10,8 @@
 import json
 
 import compas_eve as eve
-from compas_eve import JsonMessageCodec, MessageCodec
+from compas_eve import MessageCodec
+from compas_eve.codecs import JsonMessageCodec
 
 
 # Example 1: Using the default JSON codec (implicit)