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

This closes #1909
diff --git a/lib/netstd/Thrift/Thrift.csproj b/lib/netstd/Thrift/Thrift.csproj
index 5d8a9c3..783b9e9 100644
--- a/lib/netstd/Thrift/Thrift.csproj
+++ b/lib/netstd/Thrift/Thrift.csproj
@@ -19,7 +19,7 @@
   -->
 
   <PropertyGroup>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFramework>netstandard2.1</TargetFramework>
     <AssemblyName>Thrift</AssemblyName>
     <PackageId>Thrift</PackageId>
     <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>