Bump langfuse sdk to v3 #803
Description
The LangFuse v3 sdk have some breaking interface changes, therefore we need to migrate to the latest version of langfuse sdk.
Task(s):
- Bump Langufse sdk to v3. (Check the guide)
- Make sure the traces are correctly visible in langfuse sdk with tags and user ids.
- Make sure the companion is working with the self-hosted langfuse deployed in KCP-dev.