Update serde dependency per @thiolliere (#68) & fix OpaqueBlock

paritytech/substrate#6557 (comment)

node/src/service.rs

@@ -3,7 +3,7 @@
 use std::sync::Arc;
 use std::time::Duration;
 use sc_client_api::{ExecutorProvider, RemoteBackend};
-use node_template_runtime::{self, Block, RuntimeApi};
+use node_template_runtime::{self, opaque::Block, RuntimeApi};
 use sc_service::{error::Error as ServiceError, Configuration, ServiceComponents, TaskManager};
 use sp_inherents::InherentDataProviders;
 use sc_executor::native_executor_instance;

runtime/Cargo.toml

@@ -57,7 +57,6 @@ tag = 'v2.0.0-rc5'
 version = '2.0.0-rc5'
 
 [dependencies.serde]
-default-features = false
 features = ['derive']
 optional = true
 version = '1.0.101'
@@ -178,7 +177,7 @@ std = [
     'frame-support/std',
     'grandpa/std',
     'randomness-collective-flip/std',
-    'serde/std',
+    'serde',
     'sp-api/std',
     'sp-block-builder/std',
     'sp-consensus-aura/std',