Update tails-sysadmins@ OpenPGP key

Our test suite started telling us The following key(s) will not be valid in 3 months: D113CB6D5131D34BA5F0FE9E70F4F03116525F43, 373DA2F425C9D097B95ADAD458BA940CCA0A30B4 yesterday.

Feature Branch: bugfix/15318-update-sysadmins-key

Related issues

Blocks #13245 (closed)

Original created by @intrigeri on 15318 (Redmine)

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information