root.layout signature has expired

[axelsimon]

Description of issue or feature request:
The signature for /data/root.layout has expired:

"expires": "2021-01-06T18:30:57Z",

I have not checked much further, but i expect this means apt-transport-in-toto will now fail to do anything useful, as it can't trust its root layout.

Current behaviour:
Untested, but probably prevents apt-transport-in-tot from doing its job.

Expected behaviour:
The root.layout file should have a signature which has an expiry date in the future.