migrate phpunit.xml to standard version (and omit default attributes)

Author: eduardlleshi

phpunit.xml

@@ -1,22 +1,18 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit bootstrap="vendor/autoload.php"
-         backupGlobals="false"
-         backupStaticAttributes="false"
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd"
+         bootstrap="vendor/autoload.php"
          colors="true"
          verbose="true"
-         convertErrorsToExceptions="true"
-         convertNoticesToExceptions="true"
-         convertWarningsToExceptions="true"
-         processIsolation="false"
-         stopOnFailure="false">
+>
+    <coverage>
+        <include>
+            <directory suffix=".php">src/</directory>
+        </include>
+    </coverage>
     <testsuites>
         <testsuite name="League Test Suite">
             <directory>tests</directory>
         </testsuite>
     </testsuites>
-    <filter>
-        <whitelist>
-            <directory suffix=".php">src/</directory>
-        </whitelist>
-    </filter>
-</phpunit>
+</phpunit>