Enable macOS and aarch64-linux

Author: hamishmack

flake.nix

@@ -60,11 +60,9 @@
        };
        supportedSystems = [
             "x86_64-linux"
-            # Currently no aarch64 linux builders
-            # "aarch64-linux"
-            # TODO put these back (macOS hydra builders are currently down)
-            # "x86_64-darwin"
-            # "aarch64-darwin"
+            "aarch64-linux"
+            "x86_64-darwin"
+            "aarch64-darwin"
        ];
     in let flake-outputs = flake-utils.lib.eachSystem supportedSystems (system:
       let