Replace storage version to pallet version

[xlc]

https://github.com/paritytech/substrate/blob/fb4f3ecb89ce4c3f144636a9ce9766325946dd58/frame/vesting/src/lib.rs#L202

https://github.com/paritytech/substrate/blob/fb4f3ecb89ce4c3f144636a9ce9766325946dd58/frame/scheduler/src/lib.rs#L275

https://github.com/paritytech/substrate/blob/fb4f3ecb89ce4c3f144636a9ce9766325946dd58/frame/democracy/src/lib.rs#L478

They should be migrated to use pallet version.

I guess no need to add another migration unless necessary, so the migration can happen on next migration.

[bkchr]

This is more about moving over to StorageVersion, but no the custom defined one ;)

Like this one here:
https://github.com/paritytech/substrate/blob/master/frame/collective/src/lib.rs#L170-L176

[gitwithterrence]

Hello @bkchr and @xlc can I take this on?

[bkchr]

Yes you can! :)