build(deps): bump github.com/danmestas/go-libfossil to v0.15.0 check-in: 68eae8b0c9 user: [email protected] tags: main, trunk

Moves the root, leaf and bridge modules from v0.14.0 to v0.15.0, which adds horizon cones (draft-fossil-horizon-00): content and structural horizons for clones and stores, horizon serving, and the sparse-clone fixes that let cone and horizon clones of a real-sized repository complete. The only exported change that is not an addition is that cli.RepoCloneCmd is no longer comparable with ==; EdgeSync does not use it, so no code changes are needed. check-in: 8e55c6027c user: 41898282+github-actions[bot]@users.noreply.github.com tags: main, trunk