[TASK] Configure PHPUnit to be more strict (#743)

Author: oliverklee

phpunit.xml

@@ -2,9 +2,13 @@
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/8.5/phpunit.xsd"
     beStrictAboutChangesToGlobalState="true"
+    beStrictAboutOutputDuringTests="true"
+    beStrictAboutTodoAnnotatedTests="true"
     cacheResult="false"
     colors="true"
+    convertDeprecationsToExceptions="true"
     forceCoversAnnotation="true"
+    verbose="true"
 >
     <testsuites>
         <testsuite name="Project Test Suite">