flake.lock: Update

Flake lock file updates:

• Updated input 'fenix/rust-analyzer-src':
    'github:rust-lang/rust-analyzer/8e581ac348e223488622f4d3003cb2bd412bf27e' (2024-04-03)
  → 'github:rust-lang/rust-analyzer/e4a405f877efd820bef9c0e77a02494e47c17512' (2024-03-31)
• Updated input 'neovim-nightly-overlay':
    'github:nix-community/neovim-nightly-overlay/cc3b95fd0c45924babac9195d2a3b345c138866b' (2024-04-06)
  → 'github:nix-community/neovim-nightly-overlay/ba167d4057f796b93a72c081fe8657327b3775b8' (2024-04-07)
• Updated input 'neovim-nightly-overlay/neovim-flake':
    'github:neovim/neovim/a4e4e493df5f6897345278a460cccd175f7f4cf0?dir=contrib' (2024-04-05)
  → 'github:neovim/neovim/98d687a4e18161663480aa1d5ee9aff5fdf5fb57?dir=contrib' (2024-04-06)
• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/fd281bd6b7d3e32ddfa399853946f782553163b5' (2024-04-03)
  → 'github:NixOS/nixpkgs/ff0dbd94265ac470dda06a657d5fe49de93b4599' (2024-04-06)
• Updated input 'rycee':
    'gitlab:rycee/nur-expressions/2f4ce51d674373b38bc2886ff39c4d30f4b50435' (2024-04-06)
  → 'gitlab:rycee/nur-expressions/a4a3c0f0215b444a056baa924fdbc8a5d18490a6' (2024-04-07)