get rid of overlay for selfprivacy-graphql-api

flake.nix

@@ -3,19 +3,32 @@
 
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs";
-    selfprivacy-overlay.url =
-      "git+https://git.selfprivacy.org/SelfPrivacy/selfprivacy-nix-repo.git";
+
+    selfprivacy-graphql-api.url =
+      "git+https://git.selfprivacy.org/SelfPrivacy/selfprivacy-rest-api.git";
+    selfprivacy-graphql-api.inputs.nixpkgs.follows = "nixpkgs";
+    # TODO nixpkgs inputs of selfprivacy-graphql-api and this flake must match!
   };
 
-  outputs = { self, nixpkgs, selfprivacy-overlay }:
+  outputs = { self, nixpkgs, selfprivacy-graphql-api }:
     let
       system = "x86_64-linux";
     in
     {
       nixosConfigurations-fun = { hardware-configuration, userdata }: {
         just-nixos = nixpkgs.lib.nixosSystem {
-          specialArgs = { inherit system selfprivacy-overlay userdata; };
-          modules = [ hardware-configuration ./configuration.nix ];
+          specialArgs = {
+            inherit
+              system
+              hardware-configuration
+              userdata;
+            selfprivacy-graphql-api =
+              selfprivacy-graphql-api.packages.${system}.default;
+          };
+          modules = [
+            hardware-configuration
+            ./configuration.nix
+          ];
         };
       };
     };