Upgrading PHPUnit to match PHP 7.4

Author: moufmouf

composer.json

@@ -24,7 +24,7 @@
         "symfony/lock": "^3 || ^4"
     },
     "require-dev": {
-        "phpunit/phpunit": "^6.1",
+        "phpunit/phpunit": "^7.5.16",
         "satooshi/php-coveralls": "^1.0",
         "symfony/cache": "^4.1.4",
         "mouf/picotainer": "^1.1",

phpunit.xml.dist

@@ -24,7 +24,7 @@
         </whitelist>
 	</filter>
     <logging>
-        <log type="coverage-html" target="build/coverage" charset="UTF-8" yui="true" highlight="true"/>
+        <log type="coverage-html" target="build/coverage"/>
         <log type="coverage-clover" target="build/logs/clover.xml"/>
     </logging>
 </phpunit>