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

This closes #1909
diff --git a/test/netstd/Server/Server.csproj b/test/netstd/Server/Server.csproj
index 44f46c9..4f2463c 100644
--- a/test/netstd/Server/Server.csproj
+++ b/test/netstd/Server/Server.csproj
@@ -19,7 +19,7 @@
   -->
 
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.0</TargetFramework>
+    <TargetFramework>netcoreapp3.0</TargetFramework>
     <AssemblyName>Server</AssemblyName>
     <PackageId>Server</PackageId>
     <OutputType>Exe</OutputType>