nix: bump the nix-dependencies group across 1 directory with 2 updates

Bumps the nix-dependencies group with 2 updates in the / directory: [nixpkgs](https://github.com/NixOS/nixpkgs) and [rust-overlay](https://github.com/oxalica/rust-overlay).


Updates `nixpkgs` from `79b35bf` to `8edc0c7`
- [Commits](https://github.com/NixOS/nixpkgs/compare/79b35bf0bda5cd110f856aa5b5b2c5ba4460dbf5...8edc0c72e3a38faf5434e40d1f19431125fe4b30)

Updates `rust-overlay` from `2776e42` to `404b7a5`
- [Commits](https://github.com/oxalica/rust-overlay/compare/2776e42828203ec89511699c8dcdedec69ab98e1...404b7a5537f0adc6e5c558a1b94612e683dec504)

---
updated-dependencies:
- dependency-name: nixpkgs
  dependency-version: 419fe0f449b3fbe3bdd53d9840288db4509ec32e
  dependency-type: direct:production
  dependency-group: nix-dependencies
- dependency-name: rust-overlay
  dependency-version: 3f4df219c0d9aa82710232324856755d51ef0b69
  dependency-type: direct:production
  dependency-group: nix-dependencies
...

Signed-off-by: dependabot[bot] <support@github.com>

flake.lock

@@ -20,11 +20,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1789844176,
-        "narHash": "sha256-COQmpo4lFIzMgUjr3ntDpjH0NwrCnf7N0uhR+6WPGP8=",
+        "lastModified": 1791487292,
+        "narHash": "sha256-tqM7xDEsaeK1p6VvRygeZ9LkQRpUUkbRT02BHv6hnTM=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "79b35bf0bda5cd110f856aa5b5b2c5ba4460dbf5",
+        "rev": "8edc0c72e3a38faf5434e40d1f19431125fe4b30",
         "type": "github"
       },
       "original": {
@@ -48,11 +48,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1789977098,
-        "narHash": "sha256-fKY4BedarKx4aR0+UOHk65hhDW8pxFytFkaUi0VYDYk=",
+        "lastModified": 1791795448,
+        "narHash": "sha256-12C5ef8a3endLXBvLOVR/jynM9EHGgP1t+y5uBorwx4=",
         "owner": "oxalica",
         "repo": "rust-overlay",
-        "rev": "2776e42828203ec89511699c8dcdedec69ab98e1",
+        "rev": "404b7a5537f0adc6e5c558a1b94612e683dec504",
         "type": "github"
       },
       "original": {