cache-tree: use given repo's hash_algo at verify_one()

cache-tree: use given repo's hash_algo at verify_one()

verify_one() takes a struct repository argument but uses the_hash_algo
internally. Replace it with the provided repo's git_hash_algo, for
consistency. For now, this is mainly a cosmetic change, as all callers
of this function currently only pass the_repository to it.

Signed-off-by: Matheus Tavares <redacted>
Signed-off-by: Junio C Hamano <redacted>