Replaced most each() calls with foreach() in preparation to support php 8

Signed-off-by: Janos SUTO <sj@acts.hu>

webui/model/stat/chart.php

@@ -69,7 +69,7 @@ class ModelStatChart extends Model {
 
       if($query->num_rows >= 15) {
          $i = 0;
-         while(list($k, $v) = each($dates)) {
+         foreach($dates as $k => $v) {
             $i++;
             if($i % 3) { $dates[$k] = ""; }
          }