Updated Windows build script to change directory instead of copying files to run xmltest

appveyor.yml

@@ -3,5 +3,5 @@ before_build:
 
 build_script:
   - msbuild tinyxml2.sln /m /p:Configuration=Release /t:ALL_BUILD
-  - copy Release\xmltest.exe .\ && copy Release\tinyxml2.dll .\
+  - cd Release
   - xmltest.exe