Build: output test results in XML

Trying to get this to register in VSTS...

.gitignore

@@ -19,5 +19,6 @@ StackExchange.Redis.*.zip
 .idea/
 .vs/
 *.lock.json
+test-results*.xml
 packages/
 StackExchange.Redis.Tests/*Config.json

build.ps1

@@ -77,7 +77,7 @@ if ($RunTests) {
         #Push-Location ".\tests\$project"
         Push-Location ".\$project"
 
-        dotnet xunit -configuration Release
+        dotnet xunit -configuration Release -xml ./test-results.xml
         if ($LastExitCode -ne 0) {
             Write-Host "Error with tests, aborting build." -Foreground "Red"
             Pop-Location