16.0.0-rc.1

Otoroshi version 16.0.0-rc.1

https://github.com/MAIF/otoroshi/milestone/53?closed=1
v1.5.20...v16.0.0-rc.1
https://github.com/MAIF/otoroshi/releases/tag/v16.0.0-rc.1

• ensure everything is wired for the rollout of the new proxy engine (#1161)
• Remove leveldb support (#466)
• Remove mongodb support (#467)
• introduce new versioning scheme (#1275)
• Improve externals vault secrets-ttl (#1339)
• admin login does not work anymore after upgrading webauthn-server-core to 2.1.0 (#1340)
• switch lettuce as default redis driver (#1363)
• remove StoredNgTargets (#1365)