set macos frameworks explicitly (#49)

also set channel to stable (1.71)

devenv.nix

@@ -3,7 +3,12 @@
 {
 
   # https://devenv.sh/packages/
-  #packages = with pkgs; [ cargo rustc rust-analyzer rustfmt clippy maturin ];
+  # on macos frameworks have to be explicitly specified 
+  # otherwise a linker error ocurs on rust packages
+  packages = lib.optionals pkgs.stdenv.isDarwin (with pkgs.darwin.apple_sdk; [
+    frameworks.CoreServices
+    frameworks.CoreFoundation
+  ]);
 
   # Certain Rust tools won't work without this
   # This can also be fixed by using oxalica/rust-overlay and specifying the rust-src extension
@@ -21,6 +26,7 @@
 
   languages.rust = {
     enable = true;
+    channel = "stable";
     components = [ "rustc" "cargo" "clippy" "rustfmt" "rust-analyzer" ];
   };