This upgrades the Kusama system to the [Fellowship v1.2.0 release](https://github.com/polkadot-fellows/runtimes/releases/tag/v1.2.0). Most notably, this release includes the migration to Coretime.

Enactment is set for 18 April.

This upgrades the Kusama system to the [Fellowship v1.2.0 release](https://github.com/polkadot-fellows/runtimes/releases/tag/v1.2.0). Most notably, this release includes the migration to Coretime.

Upgrade Kusama v1.2.0

See [`Pallet::dispatch_whitelisted_call_with_preimage`].

- **Problem Statement:** Upgrading the Kusama system to the Fellowship v1.2.0 release, specifically migrating to Coretime.
- **Significance:** Enhancing the functionality and performance of the Kusama system.
- **Proposed Solution:** Implementing the Fellowship v1.2.0 release with Coretime migration.
- **Expected Outcomes:** Improved system efficiency and capabilities post-upgrade.

#373 Upgrade Kusama v1.2.0