Release v1.8.8

Docker reference: paritytech/substrate-relay:v1.8.8

Bundled Chain Versions:

Rococo: 1_016_001;
Westend: 1_016_001;
Kusama: 1_004_001;
Polkadot: 1_004_001;
Rococo Bridge Hub: 1_016_001;
Westend Bridge Hub: 1_016_001;
Kusama Bridge Hub: 1_007_001;
Polkadot Bridge Hub: 1_006_001;
Rococo Bulletin: not supported yet;
Polkadot Bulletin: not supported yet.

What's Changed

• bridge-hub-kusama 1.7.1 release by @rosarp in #3177

Full Changelog: v1.8.7...v1.8.8