Add upgrade boxes for 1.3.0

[conorsch]

Status

Ready for review.

Description of Changes

Last item on 1.3.0 release checklist, therefore closes #5205

Changes proposed in this pull request:

• Adds references to new "upgrade" scenario boxes (already uploaded to S3)

Testing

• Checkout develop
• make build-debs
• Check out this branch
• make upgrade-start (will take a while as it needs to fetch the boxes)
• source interface shows SecureDrop version 1.3.0
• make upgrade-test-local completes without error
• source interface shows SecureDrop version 1.4.0~rc1

Deployment

Dev only

Checklist

If you made changes to the server application code:

• Linting (make lint) and tests (make test) pass in the development container

If you made changes to securedrop-admin:

• Linting and tests (make -C admin test) pass in the admin development container

If you made changes to the system configuration:

• Configuration tests pass

If you made non-trivial code changes:

• I have written a test plan and validated it for this PR

If you made changes to documentation:

• Doc linting (make docs-lint) passed locally

If you added or updated a code dependency:

Choose one of the following:

• I have performed a diff review and pasted the contents to the packaging wiki
• I would like someone else to do the diff review

[zenmonkeykstop]

• Checkout develop
• make build-debs
• Check out this branch
• make upgrade-start (will take a while as it needs to fetch the boxes)
• source interface shows SecureDrop version 1.3.0
• make upgrade-test-local completes without error
• source interface shows SecureDrop version 1.4.0~rc1

LTGM & LUNSOTA