Fixed directory separator in appveyor

Author: JakubOnderka

appveyor.yml

@@ -25,5 +25,5 @@ install:
 
 test_script:
     - vendor\bin\tester tests -p php
-    - ./parallel-lint --exclude vendor --exclude tests/examples --no-colors .
-    - ./parallel-lint --exclude vendor --exclude tests/examples .
+    - .\parallel-lint --exclude vendor --exclude tests\examples --no-colors .
+    - .\parallel-lint --exclude vendor --exclude tests\examples .