Companion for substrate#8724 (#2994)

* runtime: create migrations for grandpa storage prefix

* runtime: address review comments

* runtime: update spec_version

* westend: fix incorrect merge

* runtime: change to v3.1 from v4 for grandpa migrations

* cargo.lock: manually specify pallet-grandpa in lock file

* cargo.lock: fix typo

* update substrate

* update substrate

Co-authored-by: André Silva <andrerfosilva@gmail.com>

polkadot/runtime/kusama/src/lib.rs

@@ -1470,6 +1470,31 @@ construct_runtime! {
 	}
 }
 
+pub struct GrandpaStoragePrefixMigration;
+impl frame_support::traits::OnRuntimeUpgrade for GrandpaStoragePrefixMigration {
+	fn on_runtime_upgrade() -> frame_support::weights::Weight {
+		use frame_support::traits::PalletInfo;
+		let name = <Runtime as frame_system::Config>::PalletInfo::name::<Grandpa>()
+			.expect("grandpa is part of pallets in construct_runtime, so it has a name; qed");
+		pallet_grandpa::migrations::v3_1::migrate::<Runtime, Grandpa, _>(name)
+	}
+
+	#[cfg(feature = "try-runtime")]
+	fn pre_upgrade() -> Result<(), &'static str> {
+		use frame_support::traits::PalletInfo;
+		let name = <Runtime as frame_system::Config>::PalletInfo::name::<Grandpa>()
+			.expect("grandpa is part of pallets in construct_runtime, so it has a name; qed");
+		pallet_grandpa::migrations::v3_1::pre_migration::<Runtime, Grandpa, _>(name);
+		Ok(())
+	}
+
+	#[cfg(feature = "try-runtime")]
+	fn post_upgrade() -> Result<(), &'static str> {
+		pallet_grandpa::migrations::v3_1::post_migration::<Grandpa>();
+		Ok(())
+	}
+}
+
 /// The address format for describing accounts.
 pub type Address = sp_runtime::MultiAddress<AccountId, ()>;
 /// Block header type as expected by this runtime.
@@ -1499,6 +1524,7 @@ pub type Executive = frame_executive::Executive<
 	frame_system::ChainContext<Runtime>,
 	Runtime,
 	AllPallets,
+	GrandpaStoragePrefixMigration,
 >;
 /// The payload being signed in the transactions.
 pub type SignedPayload = generic::SignedPayload<Call, SignedExtra>;