v4.0.0b4

What's Changed

• DataFrame output: omit timezone by default, NaN for float nulls by @wudidapaopao in #458
• Fix querying _row_number column in Parquet file by @wudidapaopao in #457
• Fix loss of nullability for DataFrame columns by @wudidapaopao in #464
• Fix concurrency issues in chDB concurrent queries by @wudidapaopao in #466

Full Changelog: v4.0.0b3...v4.0.0b4