flake.lock: Update (#1508)

Automated changes by the
[update-flake-lock](https://github.com/DeterminateSystems/update-flake-lock)
GitHub Action.

```
Flake lock file updates:

• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/9f4128e00b0ae8ec65918efeba59db998750ead6?narHash=sha256-rwz8NJZV%2B387rnWpTYcXaRNvzUSnnF9aHONoJIYmiUQ%3D' (2024-07-03)
  → 'github:NixOS/nixpkgs/7e7c39ea35c5cdd002cd4588b03a3fb9ece6fad9?narHash=sha256-EYekUHJE2gxeo2pM/zM9Wlqw1Uw2XTJXOSAO79ksc4Y%3D' (2024-07-12)
• Updated input 'released-nix-stable':
    'github:nixos/nix/39735546f1f5eee0afa40c4778cf4ba0722b5926?narHash=sha256-NH1G4GGHXU4pnQWI9X/gs7r97GO0i4tJFjoaIxl0FaQ%3D' (2024-07-05)
  → 'github:nixos/nix/f1deb42176cadfb412eb6f92315e6aeef7f2ad75?narHash=sha256-lAoLGVIhRFrfgv7wcyduEkyc83QKrtsfsq4of%2BWrBeg%3D' (2024-07-05)
• Updated input 'released-nix-unstable':
    'github:nixos/nix/41b6c735eba1ca67e58a4c62507b404e5922157b?narHash=sha256-zA6IsI0OfJ1nRTYi0t1Jb4VM/LkpIvGLIdxkaVY/dCQ%3D' (2024-07-06)
  → 'github:nixos/nix/b1effc9649e2c9103aa4b9f42fabb02b601bf80e?narHash=sha256-GyEdmaZMbjaE7yvLBsIli6E7PWR80X1hMRDoDsffOTY%3D' (2024-07-13)
• Updated input 'released-nixpkgs-stable':
    'github:NixOS/nixpkgs/c0d0be00d4ecc4b51d2d6948e37466194c1e6c51?narHash=sha256-E5dN9GDV4LwMEduhBLSkyEz51zM17XkWZ3/9luvNOPs%3D' (2024-07-04)
  → 'github:NixOS/nixpkgs/a046c1202e11b62cbede5385ba64908feb7bfac4?narHash=sha256-CWT%2BKN8aTPyMIx8P303gsVxUnkinIz0a/Cmasz1jyIM%3D' (2024-07-11)
• Updated input 'released-nixpkgs-unstable':
    'github:NixOS/nixpkgs/9f4128e00b0ae8ec65918efeba59db998750ead6?narHash=sha256-rwz8NJZV%2B387rnWpTYcXaRNvzUSnnF9aHONoJIYmiUQ%3D' (2024-07-03)
  → 'github:NixOS/nixpkgs/7e7c39ea35c5cdd002cd4588b03a3fb9ece6fad9?narHash=sha256-EYekUHJE2gxeo2pM/zM9Wlqw1Uw2XTJXOSAO79ksc4Y%3D' (2024-07-12)
```

### Running GitHub Actions on this PR

GitHub Actions will not run workflows on pull requests which are opened
by a GitHub Action.

To run GitHub Actions workflows on this PR, run:

```sh
git branch -D update_flake_lock_action
git fetch origin
git checkout update_flake_lock_action
git commit --amend --no-edit
git push origin update_flake_lock_action --force
```

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