bump json-rpc to 0.4.0 and fix test

Author: emizzle

ethers.nimble

@@ -8,7 +8,7 @@ requires "chronicles >= 0.10.3 & < 0.11.0"
 requires "chronos >= 4.0.0 & < 4.1.0"
 requires "contractabi >= 0.6.0 & < 0.7.0"
 requires "questionable >= 0.10.2 & < 0.11.0"
-requires "json_rpc >= 0.3.0 & < 0.4.0"
+requires "json_rpc >= 0.4.0 & < 0.5.0"
 requires "stint"
 requires "stew"
 requires "eth"

ethers/providers/jsonrpc/json.nim

@@ -333,9 +333,9 @@ proc fromJson*[T: ref object or object](
 
 proc fromJson*(
   _: type JsonNode,
-  json: string
+  jsn: string
 ): ?!JsonNode =
-  return parse(json)
+  return json.parseJson(jsn)
 
 proc fromJson*[T: ref object or object](
   _: type T,