Fix missing cargo-about in nix shell (#2665)

frontend/vite.config.ts formatThirdPartyLicenses needs cargo-about to be in path.
This adds cargo-about as a build dependency for both nix shells.

Co-authored-by: Keavon Chambers <keavon@keavon.com>

.nix/flake.lock

@@ -20,11 +20,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1743583204,
-        "narHash": "sha256-F7n4+KOIfWrwoQjXrL2wD9RhFYLs2/GGe/MQY1sSdlE=",
+        "lastModified": 1748190013,
+        "narHash": "sha256-R5HJFflOfsP5FBtk+zE8FpL8uqE7n62jqOsADvVshhE=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "5135c59491985879812717f4c9fea69604e7f26f",
+        "rev": "62b852f6c6742134ade1abdd2a21685fd617a291",
         "type": "github"
       },
       "original": {
@@ -36,11 +36,11 @@
     },
     "nixpkgs-unstable": {
       "locked": {
-        "lastModified": 1739214665,
-        "narHash": "sha256-26L8VAu3/1YRxS8MHgBOyOM8xALdo6N0I04PgorE7UM=",
+        "lastModified": 1748190013,
+        "narHash": "sha256-R5HJFflOfsP5FBtk+zE8FpL8uqE7n62jqOsADvVshhE=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "2c8d3f48d33929642c1c12cd243df4cc7d2ce434",
+        "rev": "62b852f6c6742134ade1abdd2a21685fd617a291",
         "type": "github"
       },
       "original": {
@@ -65,11 +65,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1743682350,
-        "narHash": "sha256-S/MyKOFajCiBm5H5laoE59wB6w0NJ4wJG53iAPfYW3k=",
+        "lastModified": 1748399823,
+        "narHash": "sha256-kahD8D5hOXOsGbNdoLLnqCL887cjHkx98Izc37nDjlA=",
         "owner": "oxalica",
         "repo": "rust-overlay",
-        "rev": "c4a8327b0f25d1d81edecbb6105f74d7cf9d7382",
+        "rev": "d68a69dc71bc19beb3479800392112c2f6218159",
         "type": "github"
       },
       "original": {

.nix/flake.nix

@@ -78,6 +78,7 @@
           pkgs.git
           pkgs.gobject-introspection
           pkgs-unstable.cargo-tauri
+          pkgs-unstable.cargo-about
 
           # Linker
           pkgs.mold

shell.nix

@@ -44,6 +44,7 @@ in
       cargo-watch
       cargo-nextest
       cargo-expand
+      cargo-about
       wasm-pack
       binaryen
       wasm-bindgen-cli