server7: aarch64 emulation

hosts/server7/default.nix

@@ -13,6 +13,8 @@ in {
     ./nix-serve.nix
   ];
 
+  boot.binfmt.emulatedSystems = [ "aarch64-linux" ];
+
   security.acme = {
     email = "mail@c3d2.de";
     acceptTerms = true;