Kyle moved to advisory, so I (Todd) will be the single signor for now.

Adding Cellular into its own Warrant Canary to include Librem AweSIM, SIMple, and SIMple plus, along with any other cellular services Purism offers.

My key expired back in February 2021 and while the private keys the old
and new public keys refers to remain the same, updating the expiry
updates the public key. This key is published on our website and in
public key servers, however it should also be published here since our
warrant canary page refers to this key.

We have updated the corresponding text file to correct a mistake in the
news source reference. I'm resigning the files.

I previously re-signed the wrong canaries (from 2019) when fixing a typo
in the 20200401 text files. I reverted that change and have now
re-signed the proper canary.

This reverts commit 4168abc5.
Accidentally re-signed the 2019 warrant canary when intending to sign
the 2020 canary.