pg_duckdb compatibility

[mrayva]

Hi! Please advise on how to proceed

You removed tuple_insert_speculative and some extension are still referencing it https://github.com/duckdb/pg_duckdb/blob/eb2c6bbbda413420e2f7c8d7806cb6b5adcde4b6/src/pgduckdb_table_am.cpp#L164