bump to php >=8.1 everywhere

Author: bendavies

phpunit.xml.dist

@@ -14,6 +14,7 @@
         <server name="SHELL_VERBOSITY" value="-1" />
         <server name="KERNEL_CLASS" value="App\Kernel" />
         <server name="PANTHER_WEB_SERVER_DIR" value="./tests/app/public" />
+        <server name="SYMFONY_DEPRECATIONS_HELPER" value="max[self]=0&amp;max[direct]=0"/>
     </php>
 
     <testsuites>