Update SDK

azure-pipelines.rx.yml

@@ -35,7 +35,7 @@ stages:
     steps:
     - task: UseDotNet@2
       inputs:
-        version: '3.0.x'
+        version: '3.1.x'
         performMultiLevelLookup: true
 
     - task: DotNetCoreCLI@2