update bundled neo-express version for RC4

Author: devhawk

package.json

@@ -327,7 +327,7 @@
   },
   "scripts": {
     "bundle-nxp": "npm run bundle-nxp-download && npm run bundle-nxp-extract",
-    "bundle-nxp-download": "shx rm -rf deps/nxp && shx mkdir -p deps/nxp && nwget \"https://github.com/neo-project/neo-express/releases/download/2.0.39-preview/Neo.Express.2.0.39-preview.nupkg\" -O deps/nxp/nxp.nupkg",
+    "bundle-nxp-download": "shx rm -rf deps/nxp && shx mkdir -p deps/nxp && nwget \"https://github.com/neo-project/neo-express/releases/download/2.0.50-preview/Neo.Express.2.0.50-preview.nupkg\" -O deps/nxp/nxp.nupkg",
     "bundle-nxp-extract": "cd deps/nxp && extract-zip nxp.nupkg",
     "compile": "npm run compile-ext && npm run compile-panel",
     "compile-ext": "webpack --config src/extension/webpack.config.js --mode development",
@@ -379,4 +379,4 @@
     "wget-improved": "^3.2.1",
     "which": "^2.0.2"
   }
-}
+}