Update live alert key

@DoctorBlue @caffeinewriter and @AbeLincoln should all be in the possession of the key with the following fingerprint before merging:
```
04:23:c3:9a:b2:2a:d0:26:b2:29:9e:ac:a5:f2:46:
a9:ae:4e:2e:8e:a1:42:13:fa:b4:4d:71:7a:64:52:
23:9a:5a:ae:62:f6:7b:b9:df:1e:4b:a2:d6:ca:2e:
bc:c6:23:49:38:88:1c:bc:59:bd:af:b3:1c:ec:eb:
07:92:9f:7e:3a:c5:83:8d:64:86:8a:02:0b:98:c3:
e4:cc:5d:87:e1:4e:6f:6f:ff:36:ed:41:b7:32:d1:
7c:12:22:bb:c6:f6:66
```

Testnet commit shortly.