Update phpstan.neon.dist

Author: tomkyle

phpstan.neon.dist

@@ -22,7 +22,7 @@ parameters:
 		# phpstan lets me down after changing some return type documentations throughout the code base
 		# by halucinating actual return tpes which aren’t there. For today, I give this up.
 
-		- message: '#should return array<int|string, mixed> but returns array<mixed, mixed>#'
+		- message: '#should return array<int\|string, mixed> but returns array<mixed, mixed>#'
 		  paths:
 		  - %currentWorkingDirectory%/src/Psr6CacheMatomoApiClient.php
 		  - %currentWorkingDirectory%/src/MatomoApiClient.php