[v0.0.6-rc6] pre-audit release

What's Changed

• fix: zero hash by @byeongsu-hong in #32
• feat: domain-routing-hook by @hashableric in #33
• fix: make MultisigIsm verifiable by @hashableric in #37
• feat: default-hook by @hashableric in #34
• [HPL-717]: test v3 codes by @hashableric in #36
• fix: default merkle tree to smt by @byeongsu-hong in #39
• ready to accept Neutron (test-tube) by @byeongsu-hong in #41
• refactor Cargo.toml by @byeongsu-hong in #42
• flexible hrp acceptance by @byeongsu-hong in #43
• refactor code structure before write some logic by @byeongsu-hong in #44
• feat(v3): hyperlane core implementation by @byeongsu-hong in #45
• pre-audit works by @byeongsu-hong in #48
• v0.0.6-rc6 by @byeongsu-hong in #57

Full Changelog: v0.0.6-rc3...v0.0.6-rc6