Bumps multihash-codetable to 0.2.2 (rsky-common, rsky-video) and updates multihash to 0.19.5, multihash-derive to 0.9.3, and cid to 0.11.3, none of which depend on the yanked core2 0.4.0. Also removes rsky-feedgen's unused serde_ipld_dagcbor 0.3 dependency, which pulled core2 via cid 0.8.6. core2 no longer appears in Cargo.lock.