Update flake.lock (#549)

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

```
Flake lock file updates:

• Updated input 'devenv':
    'github:cachix/devenv/6e82f48' (2026-03-17)
  → 'github:cachix/devenv/a5e5a7f' (2026-03-17)
• Updated input 'fenix':
    'github:nix-community/fenix/350a4df' (2026-03-16)
  → 'github:nix-community/fenix/0aa13c1' (2026-03-17)
• Updated input 'fenix/nixpkgs':
    'github:nixos/nixpkgs/5a88de7' (2026-03-15)
  → 'github:nixos/nixpkgs/5b2c2d8' (2026-03-16)
• Updated input 'fenix/rust-analyzer-src':
    'github:rust-lang/rust-analyzer/90c8906' (2026-03-15)
  → 'github:rust-lang/rust-analyzer/2993637' (2026-03-16)
• Updated input 'home-manager':
    'github:nix-community/home-manager/57d5560' (2026-03-16)
  → 'github:nix-community/home-manager/d47357a' (2026-03-18)
• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/5b2c2d8' (2026-03-16)
  → 'github:NixOS/nixpkgs/cda4854' (2026-03-17)
• Updated input 'nixpkgs-stable':
    'github:NixOS/nixpkgs/5560a08' (2026-03-16)
  → 'github:NixOS/nixpkgs/bc76f1a' (2026-03-17)
• Updated input 'rust-overlay':
    'github:oxalica/rust-overlay/1a9ddeb' (2026-03-17)
  → 'github:oxalica/rust-overlay/f17186f' (2026-03-18)
```

### 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
```

Author: github-actions[bot]