Fixed PHP 8.2 Compatiblilty.

Closes #3509732

src/EasychartUpdate.php

@@ -2,6 +2,8 @@
 
 namespace Drupal\easychart;
 
+use Drupal\Component\Utility\Unicode;
+
 /**
  * Update helper class.
  */
@@ -63,7 +65,7 @@ class EasychartUpdate {
     $enc = preg_replace_callback(
       '/"(.*?)"/s',
       function ($field) {
-        return urlencode(utf8_encode($field[1]));
+        return urlencode(Unicode::convertToUtf8($field[1], 'ISO-8859-1'));
       },
       $enc
     );
@@ -73,7 +75,7 @@ class EasychartUpdate {
         $fields = $trim_fields ? array_map('trim', explode($delimiter, $line)) : explode($delimiter, $line);
         return array_map(
           function ($field) {
-            return str_replace('!!Q!!', '"', utf8_decode(urldecode($field)));
+            return str_replace('!!Q!!', '"', Unicode::convertFromUtf8(urldecode($field), 'ISO-8859-1'));
           },
           $fields
         );