Release v0.1.1

This release makes binary-only changes. Once installed and loaded, any
existing use of chdb and chdb_hook v0.1 will get the v0.1.1 benefits without
needing to ALTER EXTENSION UPDATE.

⚡ Improvements

• Support mapping BFloat16 to Postgres real, and Interval types to Postgres interval (#76).
• Added PostgreSQL 15 support.
• Map UInt64, Int128, Int256, UInt128, and UInt256 to Postgres numeric, so values above the bigint range no longer raise an error. A derived column carries the precision spanning its chDB type (#78).

🐞 Bug Fixes

• DateTime64 or Time64 now defaults to millisecond precision (#76).
• Reading a ClickHouse string into a text column validates its bytes against database encoding, raising an error instead of returning unreadable text. Use bytea to preserve raw bytes (#80).
• Added the date_time_output_format='iso' setting to each chDB query to always format timestamp and timestamptz values in plain text formats with the ISO-8601 format in UTC, converting timestamp values from the current timezone setting.

💅🏻 Quality

• Added comprehensive tests for timestamp and timestamptz COPY output and round-tripping, including the impact of the timezone setting on timestamp values.

📚 Documentation

• Added the "Timestamp Conversion" section to the chdb_hook docs to document the ISO-8601 format of plain text exports of timestamp and timestamptz values, as well as the impact of the timezone setting on exported and imported values.
• Added a benchmark and documented its results in the README.

---

🆚 For more detail compare changes since v0.1.0.