Release 2021-09-28 schemas for v3.0 and v3.1

[jdesrosiers]

This will publish the 2021-09-28 schemas for v3.0 and v3.1 to the website so they can be downloaded by their $id.

• https://spec.openapis.org/oas/3.0/schema/2021-09-28
• https://spec.openapis.org/oas/3.1/schema/2021-09-28
• https://spec.openapis.org/oas/3.1/schema-base/2021-09-28

[karenetheridge]

Are these files also downloadable with URIs that don't include dates?

These exist:
https://spec.openapis.org/oas/3.1/dialect/base
https://spec.openapis.org/oas/3.1/meta/base

But these don't:
https://spec.openapis.org/oas/3.1/schema-base
https://spec.openapis.org/oas/3.1/schema

[jdesrosiers]

I think they should be available without dates. This came up the other day, but I haven't put up a PR yet to add them.