[duckdb-labs bot] Bump DuckDB submodule (#400)

Bump duckdb submodule:
- Target branch: v1.4-andium
- Date: 2026-03-25 08:57:35
- DuckDB SHA: 81e1e825cabc51a1caf33473bfbd8218c952eb4e
- Trigger:
https://github.com/duckdb/duckdb-python/actions/runs/23530804402

Author: evertlammerts