Remove useless phpunit/php-code-coverage dev-dependency

Signed-off-by: William Desportes <[email protected]>

Author: williamdes

composer.json

@@ -21,7 +21,6 @@
     },
     "require-dev": {
         "sami/sami": "^4.0",
-        "phpunit/php-code-coverage": "*",
         "phpunit/phpunit": "~4.8 || ~5.7 || ~6.5 || ^7.0",
         "squizlabs/php_codesniffer": "~2.9 || ~3.4"
     },