flake.lock: Update (#276)

Flake lock file updates:

• Updated input 'neovim-nightly':
    'github:nix-community/neovim-nightly-overlay/cc2d148e283e05cce751c5cc50ce38bbc0589f61?narHash=sha256-Dk%2BZTVu3CuVv4UPbif3GmR7eT3zAE/mQ%2B3UUvFHknKE%3D' (2024-06-21)
  → 'github:nix-community/neovim-nightly-overlay/8fbf3ad99db5af164230b7965de5572ce238c0da?narHash=sha256-6DlzbOUC14DN3ChG6YDfHp3dlyRunlCuNIGiJ0/j0SU%3D' (2024-06-23)
• Updated input 'neovim-nightly/neovim-src':
    'github:neovim/neovim/0e3e1e6b6d8370f1fcc9887d5cb931b131450a1c?narHash=sha256-TLJ8xTHKgnbsMnlmfQ7eF5%2Baafjo5PlFQFF3mkrIsBs%3D' (2024-06-20)
  → 'github:neovim/neovim/6c3f7e7e27a0ffcf6d58dc1f5ad2fce7e59a2d88?narHash=sha256-C2stSASvUp0XHljA6iZfDFHSH0JIDJ0g7g0uQUIHU2E%3D' (2024-06-22)
• Updated input 'neovim-nightly/nixpkgs':
    'github:NixOS/nixpkgs/9b10b8f00cb5494795e5f51b39210fed4d2b0748?narHash=sha256-jab3Kpc8O1z3qxwVsCMHL4%2B18n5Wy/HHKyu1fcsF7gs%3D' (2024-06-20)
  → 'github:NixOS/nixpkgs/90338afd6177fc683a04d934199d693708c85a3b?narHash=sha256-%2B1xgeIow4gJeiwo4ETvMRvWoircnvb0JOt7NS9kUhoM%3D' (2024-06-21)
• Updated input 'nixpkgs':
    'github:nixos/nixpkgs/90338afd6177fc683a04d934199d693708c85a3b?narHash=sha256-%2B1xgeIow4gJeiwo4ETvMRvWoircnvb0JOt7NS9kUhoM%3D' (2024-06-21)
  → 'github:nixos/nixpkgs/9693852a2070b398ee123a329e68f0dab5526681?narHash=sha256-jHJSUH619zBQ6WdC21fFAlDxHErKVDJ5fpN0Hgx4sjs%3D' (2024-06-22)

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>