Upgrade to runtime v1.20.0

Updates Kintsugi to the latest runtime (breaking). This contains, but is not limited to, the following changes:

• Updates core dependencies to polkadot-v0.9.31
• Updates to the new weight handling system

Releases

For more details, please see the following:

• https://github.com/interlay/interbtc/releases/tag/1.20.0
• https://github.com/paritytech/polkadot/releases/tag/v0.9.31

The latest compatible clients release for this version is v1.18.0:

• https://github.com/interlay/interbtc-clients/releases/tag/1.18.0

Request to fast-track the referendum to execute on 1 December 2022 10am UTC.

Proposal

• https://polkadot.js.org/apps/?rpc=wss%3A%2F%2Fapi-kusama.interlay.io%2Fparachain#/extrinsics/decode/0x0202085502aea2be02e2d56b6910f263e47bfa43ac0655ba96574b74d53949d82ab94218404500147661756c749d0168747470733a2f2f6769746875622e636f6d2f696e7465726c61792f696e7465726274632d636c69656e74732f72656c65617365732f646f776e6c6f61642f312e31382e302f7661756c742d70617261636861696e2d6d657461646174612d6b696e747375676938a6b61f1186d0ff091533ff49e9975580e411e48e9ce68b2e40ff50b6f76bd8
• Code hash: 0xaea2be02e2d56b6910f263e47bfa43ac0655ba96574b74d53949d82ab9421840