docs: Add Python 3.9+ requirement to release notes

Author: lukekim

docs/release_notes/v3.1.0.md

@@ -90,6 +90,10 @@ The optional dependencies are:
 - `adbc-driver-flightsql>=1.0.0`
 - `adbc-driver-manager>=1.0.0`
 
+## Requirements
+
+- **Python 3.9+** (minimum supported version)
+
 ## Breaking Changes
 
 None. This release is fully backward compatible with v3.0.0.
@@ -106,7 +110,7 @@ Execute a parameterized SQL query using ADBC.
 
 **Parameters:**
 - `sql` (str): SQL query with positional placeholders ($1, $2, etc.)
-- `params` (List[Any]): List of parameter values (can be plain Python values or Param instances)
+- `params` (list[Any]): List of parameter values (can be plain Python values or Param instances)
 
 **Returns:**
 - `pyarrow.RecordBatchReader`: Arrow RecordBatchReader with query results