ci: check runtime migrations

[liamaharon]

Partial paritytech/polkadot-sdk#481

Creates CI jobs to help ensure a substrate change does not accidentally break runtime upgrades on polkadot/kusama/westend/rococo.

e.g. if a pallet is updated to a new version and requires a migration but no migration is included in a companion PR to apply the migration on-chain, the CI will fail.

[ggwpez]

This does not quite prevent it, since we can still forget to bump the pallet version, or?
But we can add a subsequent job to check that if the storage metadata of a pallet was changed that the version got bumped.

e.g. if a pallet is updated to a new version and requires a migration but no migration is included in a companion PR to apply the migration on-chain, the CI will fail.

We already have this check in Polkadot, now you also want to run it in the companion CI or what exactly is this changed aiming at?

[liamaharon]

The check we added in polkadot will catch if we accidentally break it in a polkadot PR, but it will not catch if we accidentally push a change in substrate (e.g. update the pallet version) but forget to create a valid companion PR.

This recently happened in this substrate PR #14251, where the migration was written but it was forgotten to add the migration to the Migrations tuple in the companion: paritytech/polkadot#7309 (comment)

[alvicsam]

A small cleanup (this rule is defined in the .test-refs-no-trigger-prs-only)

[liamaharon]

bot merge

[paritytech-processbot]

Error: Statuses failed for bc1b0f7

[liamaharon]

I'm going to wait for the Rococo job to fix before merging this so it doesn't cause all commits to have a ❌.

The Rococo job will fix after .43 is deployed there, which @al3mart is planning this week.

[liamaharon]

bot merge

[paritytech-processbot]

Error: Statuses failed for 1448876

[liamaharon]

bot merge --force

[command-bot]

@liamaharon error: unknown option '--force'