THRIFT-4990 Switch to .NET core 3.0
Client: netstsd
Patch: Jens Geyer

This closes #1909
diff --git a/tutorial/netstd/Client/Client.csproj b/tutorial/netstd/Client/Client.csproj
index a1470a9..2abf53c 100644
--- a/tutorial/netstd/Client/Client.csproj
+++ b/tutorial/netstd/Client/Client.csproj
@@ -19,7 +19,7 @@
   -->
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.0</TargetFramework>
+    <TargetFramework>netcoreapp3.0</TargetFramework>
     <AssemblyName>Client</AssemblyName>
     <PackageId>Client</PackageId>
     <OutputType>Exe</OutputType>