Bump chronos and json-rpc and avoid http conn re-use for blockwalk (#1053)

Currently re-using http connections for the json-rpc requests
seems to slow down the requests considerably. Avoid this by
forcing a close after each requests in the blockwalk tool.

fluffy/tools/blockwalk.nim

@@ -71,6 +71,11 @@ proc walkBlocks(client: RpcClient, startHash: Hash256) {.async.} =
         fatal "Error occured on JSON-RPC request", error = e.msg
         quit 1
 
+    # Using the http connection re-use seems to slow down these sequentual
+    # requests considerably. Force a new connection setup by doing a close after
+    # each request.
+    await client.close()
+
     if parentBlockOpt.isNone():
       fatal "Failed getting parent block", hash = parentHash.data.toHex()
       quit 1

vendor/nim-chronos

@@ -1 +1 @@
-Subproject commit 3621143c89ac445d9b3264cc247c59bb4db4b1e4
+Subproject commit bb4c3298f56ba7bc69fbccd08fd6e5474c410262

vendor/nim-json-rpc

@@ -1 +1 @@
-Subproject commit b80313bfed0594198d77c6a22616f1f96c0d91fa
+Subproject commit 335f292a5816910aebf215e3a88db8a665133e0e