Use newest dotnet SDK to build C#
diff --git a/src/csharp/global.json b/src/csharp/global.json
index e4b797e..815be4b 100644
--- a/src/csharp/global.json
+++ b/src/csharp/global.json
@@ -1,5 +1,5 @@
 {
   "sdk": {
-    "version": "1.0.0"
+    "version": "2.1.4"
   }
 }