make flake generic over platform

flake.nix

@@ -8,13 +8,22 @@
 
   outputs = { self, nixpkgs, nix-filter }:
     let
-      system = "x86_64-linux";
+      forAllSystems = f: nixpkgs.lib.genAttrs
-      pkgs = import nixpkgs { inherit system; };
+        [ "x86_64-linux" "aarch64-linux" ]
+        (system: f system);
+      nixpkgsFor = forAllSystems (
+        system:
+        import nixpkgs { inherit system; }
+      );
       filter = nix-filter.lib;
     in
     {
 
-      packages.x86_64-linux = {
+      packages = forAllSystems (system:
+        let
+          pkgs = nixpkgsFor.${system};
+        in
+        {
           mobilizon = pkgs.callPackage ./. {
             src = filter {
               root = ./.;
@@ -38,9 +47,12 @@
 
               ${pkgs.mix2nix}/bin/mix2nix ./mix.lock > mix.nix
             '';
-      };
+        });
 
-      devShells.x86_64-linux.default =
+      devShells = forAllSystems (system:
+        let pkgs = nixpkgsFor.${system};
+        in {
+          default =
             pkgs.mkShell {
               buildInputs = with pkgs; [
                 elixir
@@ -54,10 +66,11 @@
                 nodejs-18_x
               ];
             };
+        });
 
-      checks.x86_64-linux = {
+      checks = forAllSystems (system: {
-        inherit (self.packages.x86_64-linux) mobilizon update;
+        inherit (self.packages.${system}) mobilizon update;
-      };
+      });
 
       lib = {
         # Patch the logos in the source tree of a mobilizon-frontend package before building.
@@ -67,7 +80,6 @@
             inherit (icons) logo favicon;
           in
           old: {
-            nativeBuildInputs = (old.nativeBuildInputs or [ ]) ++ [ pkgs.imagemagick ];
             postPatch = ''
               cp '${logo}' src/assets/logo.svg