Remove coveralls integration

Author: chadicus

.coveralls.yml

@@ -39,7 +39,6 @@
         "traderinteractive/filter-strings": "^3.6"
     },
     "require-dev": {
-        "php-coveralls/php-coveralls": "^2.0",
         "phpunit/phpunit": "^6.0",
         "squizlabs/php_codesniffer": "^3.2",
         "symfony/yaml": "^3.4"