Bumped phpstan level up to 5

Can bump the level that high with (almost) no errors.

Author: james-hill-matomo

ScheduleReportSlack.php

@@ -37,10 +37,6 @@ class ScheduleReportSlack
      */
     private $token;
 
-    /**
-     * @var string
-     */
-
     public function __construct(
         string $subject,
         string $fileName,

phpstan.neon

@@ -1,5 +1,5 @@
 parameters:
-    level: 0
+    level: 5
     phpVersion: 70200
     tmpDir: /tmp/phpstan/Slack/main
     paths:
@@ -16,4 +16,5 @@ parameters:
         # ../../ does not actually seem to give us anything
         # that ../plugins/ does not, but including it for
         # completeness.  It does not seem to slow down performance.
-        - ../../
+        - ../../
+