flake.lock: Update

Flake lock file updates:

• Updated input 'emacs-overlay':
    'github:nix-community/emacs-overlay/0f0e97805c949e227df8503df13335fad57f271d' (2023-08-05)
  → 'github:nix-community/emacs-overlay/65b4af301be5a4ed08899f5cc183d16ed7c2daa1' (2023-08-12)
• Updated input 'emacs-overlay/nixpkgs-stable':
    'github:NixOS/nixpkgs/9652a97d9738d3e65cf33c0bc24429e495a7868f' (2023-08-04)
  → 'github:NixOS/nixpkgs/18784aac1013da9b442adf29b6c7c228518b5d3f' (2023-08-10)
• Updated input 'gnu-elpa':
    'git+https://git.savannah.gnu.org/git/emacs/elpa.git?ref=main&rev=c7a0f19aaa48504151fd7cbea2db7f0a716dfc64' (2023-07-13)
  → 'git+https://git.savannah.gnu.org/git/emacs/elpa.git?ref=main&rev=6781ce215ca153fbae6483f0a995b9bc4c9030dc' (2023-08-12)
• Updated input 'melpa':
    'github:melpa/melpa/4d9ff9717f25fd229891746044777de8a73558c2' (2023-07-30)
  → 'github:melpa/melpa/bdb191b4cd65bd60a905ec2866471031abec7f23' (2023-08-10)
• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/18036c0be90f4e308ae3ebcab0e14aae0336fe42' (2023-08-04)
  → 'github:NixOS/nixpkgs/ce5e4a6ef2e59d89a971bc434ca8ca222b9c7f5e' (2023-08-10)
• Updated input 'nongnu-elpa':
    'git+https://git.savannah.gnu.org/git/emacs/nongnu.git?ref=main&rev=65b952d31a34ef72328b66af55d0a526917a86b1' (2023-08-04)
  → 'git+https://git.savannah.gnu.org/git/emacs/nongnu.git?ref=main&rev=14e9631cd2b81f66ed551b14d31811a75cc53a4b' (2023-08-08)