Handle relocation of ParachainHost in Polkadot (#1108)

* Handle relocation of `ParachainHost` in Polkadot

`ParachainHost` is no longer versioned and is in `runtime_api` module.

This is a companion for
https://github.com/paritytech/polkadot/pull/5048

* Update dependencies

primitives/core/src/lib.rs

@@ -35,7 +35,7 @@ pub use polkadot_primitives::v2::{
 /// A module that re-exports relevant relay chain definitions.
 pub mod relay_chain {
 	pub use polkadot_core_primitives::*;
-	pub use polkadot_primitives::{v2, v2::well_known_keys};
+	pub use polkadot_primitives::{runtime_api, v2, v2::well_known_keys};
 }
 
 /// An inbound HRMP message.