Allow retract_tip on tip_new (#6511)

* Allow `retract_tip` on `tip_new`

* initial migration code

* test migration

* make pub

* bump spec

substrate/bin/node/runtime/src/lib.rs

@@ -97,8 +97,8 @@ pub const VERSION: RuntimeVersion = RuntimeVersion {
 	// and set impl_version to 0. If only runtime
 	// implementation changes and behavior does not, then leave spec_version as
 	// is and increment impl_version.
-	spec_version: 254,
-	impl_version: 1,
+	spec_version: 255,
+	impl_version: 0,
 	apis: RUNTIME_API_VERSIONS,
 	transaction_version: 1,
 };