Check for search dim mismatch

[uros-r]

... to prevent downstream memory / segfault issues.

With a clean hnsqlite Python 3.10 venv and latest project deps on a Mac, the TestCollection2.test_search_invalid test fails for me with either

Python(39103,0x10bba4600) malloc: Incorrect checksum for freed object 0x7fa668a7d508: probably modified after being freed. Corrupt value: 0x8000000000000000

or occasionally an outright segmentation fault.

This PR adds a simple dim mismatch check in Collection.search.