[FIX] website_form: replace False and None by ""

In python false is written `False` however JSON only support the notation
`false` otherwise JSON.parse fails
Again in python a null value is written `None` however `None` is `null`
in JSON notation

A solution to this incompatibility problem between python and javascript
can be to replace `False` and `None`by empty strings on the javascript
side.

closes odoo/odoo#34995

Signed-off-by: Romain Libert (rli) <rli@odoo.com>

addons/website_form/static/src/js/website_form.js

@@ -57,7 +57,7 @@ odoo.define('website_form.animation', function (require) {
             // Because, using t-att- inside form make it non-editable
             var $values = $('[data-for=' + this.$target.attr('id') + ']');
             if ($values.length) {
-                var values = JSON.parse($values.data('values').replace(/'/g, '"'));
+                var values = JSON.parse($values.data('values').replace('False', '""').replace('None', '""').replace(/'/g, '"'));
                 var fields = _.pluck(this.$target.serializeArray(), 'name');
                 _.each(fields, function (field) {
                     if (_.has(values, field)) {