Use latest build of dotnet-test-xunit

Author: pranavkm

test/dotnet-razor-tooling.Test/project.json

@@ -8,7 +8,7 @@
           "type": "platform"
         },
         "dotnet-razor-tooling": "1.0.0-*",
-        "dotnet-test-xunit": "1.0.0-dev-*",
+        "dotnet-test-xunit": "1.0.0-*",
         "Microsoft.AspNetCore.Razor.Test.Sources": {
           "version": "1.0.0-*",
           "type": "build"