Bump DotNet SDK to 3.1 for Sonar

azure-pipelines.yaml

@@ -31,10 +31,10 @@ stages:
               packageType: sdk
               version: 5.0.x
           - task: UseDotNet@2
-            displayName: 'Install .NET Core SDK 2.0'
+            displayName: 'Install .NET Core SDK 3.1'
             inputs:
               packageType: sdk
-              version: 2.0.x
+              version: 3.1.x
           - task: SonarSource.sonarcloud.14d9cde6-c1da-4d55-aa01-2965cd301255.SonarCloudPrepare@1
             displayName: Start SonarQube Analysis
             inputs: