Added template for film scanner firmware

firmware/shell.nix

@@ -1,10 +1,12 @@
 { pkgs ? import <nixpkgs> {} }:
 
 pkgs.mkShell {
-  buildInputs = [
-    pkgs.stdenv
-
+  buildInputs = with pkgs; [
+    tio
+    stdenv
+    elf2uf2-rs
+    probe-run
     # keep this line if you use bash
-    pkgs.bashInteractive
+    bashInteractive
   ];
 }