Remove creation of a list for row_cast_map in pysqlite_cursor_init().

[sir-sigurd]

This list is never used: if detect_types is on, this list will be replaced with another one before row_cast_map is used, if detect_types is off, row_cast_map is not used at all.

[zooba]

I trust your analysis, but I don't trust my own checking of your analysis :) Could you add a null check at line 252?

if (self->connection->detect_types && self->row_cast_map) {

(Or alternatively, add an assertion inside the block)