[TASK] Be less strict about the @covers annotation (#686)

We still want to require the `@covers` annotation to be used for
testcase (`forceCoversAnnotation="true"`), but we also want to be
able to indirectly execute code that is not referenced via an
`@covers` annotation.

Author: oliverklee

phpunit.xml

@@ -2,7 +2,6 @@
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/8.5/phpunit.xsd"
     beStrictAboutChangesToGlobalState="true"
-    beStrictAboutCoversAnnotation="true"
     cacheResult="false"
     colors="true"
     forceCoversAnnotation="true"