Updated phpunit config schema to 10.0 and set cache directory

Author: Bastian Schwarz

test/phpunit.dist.xml

@@ -16,9 +16,10 @@
   -->
 <phpunit
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-  xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd"
+  xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/10.0/phpunit.xsd"
   colors="true"
   bootstrap="./bootstrap.php"
+  cacheDirectory="../.cache/phpunit"
 >
   <coverage>
     <include>