hosts: nixos: porthos: secrets: rekey secrets

Some of the secrets were using an invalid format due to (probably?)
being encrypted with a beta version of `age`.

I didn't need to rekey *all* the secrets, but I might as well

hosts/nixos/porthos/secrets/backup/password.age

@@ -1,8 +1,7 @@
 age-encryption.org/v1
--> ssh-ed25519 cKojmg dgS4bezgtDi44R1A8am+J6zh80kUVYTo1heaxJCtzX4
-F3w/62xwtqYa40NU7OvF9pnZzYz/5hACAGJfMA4e2zw
--> ssh-ed25519 jPowng lx81CK3yeNp9RjHCUFJeKYZlRzxBmXuADVBvRc13zCI
-P7e75t8xU+ZkYmeQ8mmMfyZZsRdG1J8yrvSUkiWzkFQ
--> *z4/`-grease S/)a{e sFd";=
---- 15FVhqRTkoPFEeETRRyFQhsv4Fn19Ozlax0u8Zy9mNA
-õ#+¥àÎvøSÈ4èá}<7D>§Rì%‹Î¯F4fnDœ˜J¹¤Z‹¸A¥Û™,_
+-> ssh-ed25519 cKojmg O3DMSSPQP9/ehXmzs0xcCGllu7VSzhd6b4Pii8t2vWQ
+Ys1nMv2384elWWGW9C8HabvwUeWu52VsQpxx9L/4/dM
+-> ssh-ed25519 jPowng ft/9SX5fpG7+7gHMubaFtb+50/gfNgmaofOVq5UjRUE
+xMwdFjFdkH0Li+PikaFt0WAZbFUu5daHgkfN8aQQumo
+--- 7DVINvXIXdE1MRwIkeajonYsy1cp4HugCxfTeub5SXU
+<¥ö¡Ãñ<ýØ{VÇ?ñfk/¤áI®"<22>ï×/5K"Š¸(ì¢ùiÃÔôìñ