fix: UptimeKuma Up/Down counts are always zero (#824)

Fix UptimeKuma::livestats() function. An incorrect !== operator, that should be
===, prevent the monitor_status metric lines from being counted by livestats().

Author: wblew

UptimeKuma/UptimeKuma.php

@@ -62,7 +62,7 @@ public function livestats()
                 continue;
             }
 
-            if (strpos($line, 'monitor_status') !== 0) {
+            if (strpos($line, 'monitor_status') === 0) {
                 // If the line is a metric but not a monitor we can ignore it
                 continue;
             }