Update tails-sysadmins@ OpenPGP key

Originally created by @intrigeri on #15318 (Redmine)

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 tails#13245 (closed)

Edited May 15, 2020 by intrigeri

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