chore: update ably-common to a revision carrying the msgpack fixtures

The msgpack interop specifications read test-resources/msgpack_test_fixtures.json,
which the pinned revision predated, so those tests were gated on the file being
present. They now run.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: owenpearson