Use attic as nixos binary cache and update CI accordingly

secrets/atticd-credentials.age

@@ -0,0 +1,8 @@
+age-encryption.org/v1
+-> ssh-ed25519 hPp1nw tMy5kLAcQD62yAfEVJ4LQZjs0kkEEQOfM4HN9yj3hBY
+JvlklGTxxfAZbP+alm3nxLxqhmcu2mTKwRU5WaapL9w
+-> ssh-ed25519 w3nu8g ZGzufldXq7kmIpqFecbkpDxiykWZ207k0+09I2dmxEM
+SK25e5HBe4b5reGXXfCjIFbFGzfu32RFjY++/yteRVc
+--- xZOe1syYAcVRDhiNRv+CsfFgoQbiANA6vNCon+5NExc
+-·ñ1Å,C-.M§Áè?ÐêóµµàY|u+
+‹	³Ø�÷ŽæÒ¡ôm†Œûäfß]=érøÜüÎAg¤€æSú:Ð8•S¦LiœùªsêÁâ9JŠð<>¸ÏæñÄÐÃ<ûAz¹[ý§xï�:‡'U*�wÀ™D/…±VpM~!õ,* ¿”µ¡øk¥Ö´ßEíîïh› {¢p$¾R`ÿ”

secrets/secrets.nix

@@ -20,10 +20,7 @@ with roles;
   "robots-email-pw.age".publicKeys = gitea;
 
   # nix binary cache
-  # public key: s0.koi-bebop.ts.net:OjbzD86YjyJZpCp9RWaQKANaflcpKhtzBMNP8I2aPUU=
-  "binary-cache-private-key.age".publicKeys = binary-cache;
-  # public key: ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAINpUZFFL9BpBVqeeU63sFPhR9ewuhEZerTCDIGW1NPSB
-  "binary-cache-push-sshkey.age".publicKeys = nobody; # this value is directly given to gitea
+  "atticd-credentials.age".publicKeys = binary-cache;
 
   # vpn
   "iodine.age".publicKeys = iodine;