The big breaking change for our code (not mentioned in the changelog) is
that the built-in validator for the `date-time` format now requires the
`rfc3339-validator` package instead of the `strict-rfc3339` package.
This updates the requirements file to use `rfc3339-validator`. Without
this change, wrong `date-time` formats would always silently pass validation.
We were using the Draft4Validator in one place, so this updates it to
the Draft7Validator instead.
The schemas were mostly using draft 4 of the JSON schema, though there
were a couple of schemas that were already of version 7. This updates
them all to version 7, which is the latest version fully supported by
the jsonschema Python package. There are some breaking changes in the
newer version of the schema, but I could not see anywhere would these
affect us. Some of these schemas were not valid in version 4, but are
now valid in version 7 because `"required": []` was not valid in earlier
versions.
This relationship is via the `Organisation` now; we don’t use this
column to fudge a relationship based on the user’s email address and the
matching something in these columns.
However, until we can create a letter without a logo, we will still default to hm-government, because the dvla_organisation is set on the service.
This does simplify the code.
Also removed the inserts to letter_branding in the data migration file, because we can deploy this before the rest of the work is finished. But we will need to do it later.
