flake: update inputs (#170)

Flake lock file updates:

• Updated input 'nixos-cosmic':
    'github:lilyinstarlight/nixos-cosmic/ffa6eea20301d21932fd9870570418a4fb96204c?narHash=sha256-0iils2qitbyYQswdgiSOeateOVsKRjhJqGaSNFWKRHE%3D' (2025-01-09)
  → 'github:lilyinstarlight/nixos-cosmic/a934c861065b6b1aca9a859c45631336e0e8560c?narHash=sha256-h6hi94y9bTl9DQV4keGpYAfJhnH50rxxEdQlGL7QENw%3D' (2025-01-11)
• Removed input 'nixos-cosmic/rust-overlay'
• Removed input 'nixos-cosmic/rust-overlay/nixpkgs'
• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/8f3e1f807051e32d8c95cd12b9b421623850a34d?narHash=sha256-/qlNWm/IEVVH7GfgAIyP6EsVZI6zjAx1cV5zNyrs%2BrI%3D' (2025-01-04)
  → 'github:NixOS/nixpkgs/bffc22eb12172e6db3c5dde9e3e5628f8e3e7912?narHash=sha256-8YVQ9ZbSfuUk2bUf2KRj60NRraLPKPS0Q4QFTbc%2Bc2c%3D' (2025-01-08)

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