Schema.org validator examples do not work

[mhkuu]

It seems that our method of POSTing snippets to validator.schema.org no longer works. We instead receive a 403 error.

See e.g. https://developer.yoast.com/features/schema/functional-specification/ and click on "Test & modify in the Schema.org Validator".

The code resides in src/components/YoastSchemaExample/index.js.