message: Set statement handle reference to null when it's released.
diff: @@ -49,6 +49,7 @@ SQLRETURN SQLFreeHandle(SQLSMALLINT handle_type, SQLHANDLE handle) {
  }
  case SQL_HANDLE_STMT: {
  auto *hdl = (duckdb::OdbcHandleStmt *)handle;
  + hdl->dbc->stmt_handle = nullptr;
  delete hdl;
  return SQL_SUCCESS;
  }
  