use --dev phpunit

Author: ashnazg

appveyor.yml

@@ -48,8 +48,7 @@ install:
   - IF NOT EXIST php-installed.txt type nul >> php-installed.txt
   - cd c:\typeresolver
   - composer install --no-interaction --prefer-dist --no-progress
-  - composer require --dev phpunit/phpunit
 
 test_script:
   - cd c:\typeresolver
-  - ./vendor/bin/phpunit --no-coverage
+  - vendor\bin\phpunit --no-coverage