Move context from http://schema.org to https://schema.org/

[Chris Müller]

In August 2020 the schema.org website migrated their examples to use https://schema.org as context instead of http://schema.org.

There is a general trend towards using 'https' more widely, and you can already write https://schema.org in your structured data. Over time we will migrate the schema.org site itself towards using https: as the default version of the site and our preferred form in examples. However http://schema.org-based URLs in structured data markup will remain widely understood for the forseeable future and there should be no urgency about migrating existing data. This is a lengthy way of saying that both https://schema.org and http://schema.org are fine.

https://schema.org/docs/faq.html#19

As this can be "breaking" to users of the schema extension (I am thinking of unit or acceptance tests), this change should go into the next major release only.

Additionally, as the context is a URL (protocol, server, path), a trailing / is added. See also example in JSON-LD specification:
https://w3c.github.io/json-ld-syntax/#locating-a-specific-json-ld-script-element. Also the JSON-LD playground complaints about the missing / at the end.

• The CONTEXT constant in JsonLd\Renderer class is changed into https://schema.org/.
• In Model\DataType\Boolean http scheme is changed to https
• The documentation examples are adapted accordingly.
• A change log entry is added.