add treefmt and jupyter lab

treefmt.nix

@@ -0,0 +1,17 @@
+{ inputs, ... }:
+{
+  imports = [ inputs.treefmt-nix.flakeModule ];
+
+  perSystem =
+    { ... }:
+    {
+      treefmt = {
+        # Used to find the project root
+        projectRootFile = "flake.nix";
+        programs.deadnix.enable = true;
+        programs.nixfmt.enable = true;
+        programs.shellcheck.enable = true;
+        programs.yamlfmt.enable = true;
+      };
+    };
+}