Bump test runtime

eng/restore-toolset.ps1

@@ -2,35 +2,35 @@ function InitializeCustomSDKToolset {
     if (-not $restore) {
       return
     }
-  
+
     # Turn off MSBuild Node re-use
     $env:MSBUILDDISABLENODEREUSE=1
-  
+
     # Workaround for the sockets issue when restoring with many nuget feeds.
     $env:DOTNET_SYSTEM_NET_HTTP_USESOCKETSHTTPHANDLER=0
-  
+
     # Enable vs test console logging
     $env:VSTEST_BUILD_TRACE=1
     $env:VSTEST_TRACE_BUILD=1
-  
+
     $env:DOTNET_CLI_TELEMETRY_PROFILE='$env:DOTNET_CLI_TELEMETRY_PROFILE;https://github.com/dotnet/format'
-  
+
     $cli = InitializeDotnetCli -install:$true
-    InstallDotNetSharedFramework "2.1.15"
+    InstallDotNetSharedFramework "3.1.4"
   }
-  
+
   function InstallDotNetSharedFramework([string]$version) {
     $dotnetRoot = $env:DOTNET_INSTALL_DIR
     $fxDir = Join-Path $dotnetRoot "shared\Microsoft.NETCore.App\$version"
-  
+
     if (!(Test-Path $fxDir)) {
       $installScript = GetDotNetInstallScript $dotnetRoot
       & $installScript -Version $version -InstallDir $dotnetRoot -Runtime "dotnet"
-  
+
       if($lastExitCode -ne 0) {
         Write-Output "Failed to install Shared Framework $version. Ignoring failure as not all distros carrie all versions of the framework."
       }
     }
   }
-  
+
   InitializeCustomSDKToolset