THRIFT-4990: Upgrade to .NET Core 3.0
Client: netstsd
Patch: Edward Zhuravlov

This closes #1921
diff --git a/lib/netstd/Thrift/Thrift.csproj b/lib/netstd/Thrift/Thrift.csproj
index 783b9e9..5d8a9c3 100644
--- a/lib/netstd/Thrift/Thrift.csproj
+++ b/lib/netstd/Thrift/Thrift.csproj
@@ -19,7 +19,7 @@
   -->
 
   <PropertyGroup>
-    <TargetFramework>netstandard2.1</TargetFramework>
+    <TargetFramework>netstandard2.0</TargetFramework>
     <AssemblyName>Thrift</AssemblyName>
     <PackageId>Thrift</PackageId>
     <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
diff --git a/tutorial/netstd/Interfaces/Interfaces.csproj b/tutorial/netstd/Interfaces/Interfaces.csproj
index 2d8a440..4ebeb4f 100644
--- a/tutorial/netstd/Interfaces/Interfaces.csproj
+++ b/tutorial/netstd/Interfaces/Interfaces.csproj
@@ -19,7 +19,7 @@
   -->
 
   <PropertyGroup>
-    <TargetFramework>netstandard2.1</TargetFramework>
+    <TargetFramework>netstandard2.0</TargetFramework>
     <AssemblyName>Interfaces</AssemblyName>
     <PackageId>Interfaces</PackageId>
     <GenerateAssemblyConfigurationAttribute>false</GenerateAssemblyConfigurationAttribute>