flake.lock: Update (#307)

Flake lock file updates:

• Updated input 'fenix':
    'github:nix-community/fenix/c739f83545e625227f4d0af7fe2a71e69931fa4c?narHash=sha256-KcvsEm0h1mIwBHFAzWFBjGihnbf2fxpAaXOdVbUfAI4%3D' (2024-04-12)
  → 'github:nix-community/fenix/3247290e1bba55878a2c62d43894d0309d29c918?narHash=sha256-lYWehi0cqBdsL1W4xeUnUcXw4U4aBKKCmmQrR01yqE0%3D' (2024-04-20)
• Updated input 'fenix/nixpkgs':
    'github:nixos/nixpkgs/1042fd8b148a9105f3c0aca3a6177fd1d9360ba5?narHash=sha256-3sbWO1mbpWsLepZGbWaMovSO7ndZeFqDSdX0hZ9nVyw%3D' (2024-04-10)
  → 'github:nixos/nixpkgs/5c24cf2f0a12ad855f444c30b2421d044120c66f?narHash=sha256-XtTSSIB2DA6tOv%2Bl0FhvfDMiyCmhoRbNB%2B0SeInZkbk%3D' (2024-04-19)
• Updated input 'fenix/rust-analyzer-src':
    'github:rust-lang/rust-analyzer/657b33b0cb9bd49085202e91ad5b4676532c9140?narHash=sha256-VDxsvgj/bNypHq48tQWtc3VRbWvzlFjzKf9ZZIVO10Y%3D' (2024-04-11)
  → 'github:rust-lang/rust-analyzer/c83d8cf5844fff3d6e243ab408669222059af1c6?narHash=sha256-HsVa%2BQM2vMra80OjnjH7JhdvLeJuMdR4sxBNHJveMe4%3D' (2024-04-19)
• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/c27f3b6d8e29346af16eecc0e9d54b1071eae27e?narHash=sha256-RifMwYuKu5v6x6O65msKDTqKkQ9crGwOB7yr20qMEuE%3D' (2024-04-13)
  → 'github:NixOS/nixpkgs/74574c38577914733b4f7a775dd77d24245081dd?narHash=sha256-q7APLfB6FmmSMI1Su5ihW9IwntBsk2hWNXh8XtSdSIk%3D' (2024-04-20)
• Updated input 'nixpkgs-master':
    'github:NixOS/nixpkgs/1b691969594504eabec53a11a366acf1c75387d1?narHash=sha256-iw3O6mVc%2BJx7UZMnIWyzuIc0x7xN5RY0oxZ4gbFY5wU%3D' (2024-04-13)
  → 'github:NixOS/nixpkgs/754a00b38a44e774dba3518ced7efbf51a8970ba?narHash=sha256-5zVIy90Uc5LzE7rt4x7LLZZWoYVM5g40QQlAxqc7BDc%3D' (2024-04-20)