Use php-coveralls 2.1 and phpunit 7.4

Author: chdemko

composer.json

@@ -17,9 +17,9 @@
 		"php": ">=5.5.0"
 	},
 	"require-dev": {
-		"php-coveralls/php-coveralls": "^2.0",
+		"php-coveralls/php-coveralls": "^2.1",
 		"joomla/coding-standards": "~2.0@alpha",
-		"phpunit/phpunit": "^7.0",
+		"phpunit/phpunit": "^7.4",
 		"sphpdox/sphpdox": "dev-master",
 		"phpbench/phpbench": "^1.0@dev"
 	},