flake.lock: Update

Flake lock file updates:

• Updated input 'emacs-overlay':
    'github:nix-community/emacs-overlay/3fd7df8e48255363c9460e8284f5ec92a3cc4403' (2023-07-22)
  → 'github:nix-community/emacs-overlay/e9982c6dd9ef4d47aed955013820cd15104be6df' (2023-07-29)
• Updated input 'emacs-overlay/nixpkgs-stable':
    'github:NixOS/nixpkgs/fa793b06f56896b7d1909e4b69977c7bf842b2f0' (2023-07-20)
  → 'github:NixOS/nixpkgs/48e82fe1b1c863ee26a33ce9bd39621d2ada0a33' (2023-07-28)
• Updated input 'melpa':
    'github:melpa/melpa/eee4fe970e0396e443355128e90e622f7ddd8633' (2023-07-17)
  → 'github:melpa/melpa/244a0005dd705665f28c4774c343e69234c45f80' (2023-07-24)
• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/9ca785644d067445a4aa749902b29ccef61f7476' (2023-07-21)
  → 'github:NixOS/nixpkgs/2a9d660ff0f7ffde9d73be328ee6e6f10ef66b28' (2023-07-28)