[BUG] diskannpy: batch_search is mistyped

[bddap]

Expected Behavior

According to its type annotations, batch_search is expected to return a named tuple.

Actual Behavior

It returns a normal tuple.

[bddap]

Might want to check static_memory_index and _dynamic_memory_index too.

[daxpryce]

Oh man thank you for this. I'll get a fix out asap