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

This closes #1909
diff --git a/lib/netstd/Tests/Thrift.Tests/Thrift.Tests.csproj b/lib/netstd/Tests/Thrift.Tests/Thrift.Tests.csproj
index 434424d..b060182 100644
--- a/lib/netstd/Tests/Thrift.Tests/Thrift.Tests.csproj
+++ b/lib/netstd/Tests/Thrift.Tests/Thrift.Tests.csproj
@@ -18,7 +18,7 @@
     under the License.
   -->
   <PropertyGroup>
-    <TargetFramework>netcoreapp2.0</TargetFramework>
+    <TargetFramework>netcoreapp3.0</TargetFramework>
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="CompareNETObjects" Version="4.58.0" />