Fixed a couple missing .Net Platform 5.4 dependencies

src/Discord.Net/project.json

@@ -43,6 +43,7 @@
       "dependencies": {
         "System.Collections": "4.0.11-beta-23516",
         "System.Collections.Concurrent": "4.0.11-beta-23516",
+        "System.Dynamic.Runtime": "4.0.11-beta-23516",
         "System.IO.FileSystem": "4.0.1-beta-23516",
         "System.IO.Compression": "4.1.0-beta-23516",
         "System.Linq": "4.0.1-beta-23516",
@@ -54,6 +55,7 @@
         "System.Reflection": "4.1.0-beta-23516",
         "System.Reflection.Emit.Lightweight": "4.0.1-beta-23516",
         "System.Runtime.InteropServices": "4.0.21-beta-23516",
+        "System.Runtime.Serialization.Primitives": "4.1.0-beta-23516",
         "System.Security.Cryptography.Algorithms": "4.0.0-beta-23516",
         "System.Text.RegularExpressions": "4.0.11-beta-23516",
         "System.Threading": "4.0.11-beta-23516"