iframe support broken in 1.3.1

The ‘src’ attribute of iframes is not getting set in version 1.3.1, resulting in empty iframes. The following patch fixes the problem:

--- plugin.php.orig	2023-10-31 11:09:39.560071391 -0500
+++ plugin.php	2023-10-31 11:09:11.493582610 -0500
@@ -110,7 +110,7 @@ if (is_admin()) {
         if (isset($attrs['src'])) {
             $tmp = '';
             foreach ($attrs as $key => $value) {
-                if (!in_array($key, ['width', 'style', 'class', 'id', 'height'])) {
+                if (!in_array($key, ['src', 'width', 'style', 'class', 'id', 'height'])) {
                     continue;
                 }
                 $value = strip_tags($value);

Although iframe support isn’t really needed by people using the Gutenberg editor, some sites can’t use that editor for various reasons. Therefore, we really appreciate this feature of the plugin, not to mention the other goodies it provides. Thanks!