chore: switch opendal deps from local path to kszucs/opendal fork

Point opendal and object_store_opendal at kszucs/opendal@4c70bd8
(hf-revamp branch) which uses published hf-xet 1.5.0 from crates.io.

Once apache/opendal#7185 merges and publishes, these become simple
version deps (e.g. opendal = "0.56").

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: davanstrien