Update flake.lock (#11735)

flake.lock: Update

Flake lock file updates:

• Updated input 'fenix':
    'github:nix-community/fenix/b60fe116b9495df516f57837bb04a4f89f3aa7ed?narHash=sha256-p2FIwAaUCoKY9mZSPAMQYQ7CwwhfvGC4VIfLapAdfOE%3D' (2025-09-17)
  → 'github:nix-community/fenix/bfa40349cb508ebec2a8d0f89d65022967d28dc4?narHash=sha256-xpbGgQ6ymKvz/LQ3RrUTHdbRKWznZAbdaNAH7TdbKZs%3D' (2025-09-20)
• Updated input 'fenix/rust-analyzer-src':
    'github:rust-lang/rust-analyzer/9edc9cbe5d8e832b5864e09854fa94861697d2fd?narHash=sha256-/PAhxheUq4WBrW5i/JHzcCqK5fGWwLKdH6/Lu1tyS18%3D' (2025-09-08)
  → 'github:rust-lang/rust-analyzer/b12a1293473d4c1c74a63752184b8d21d32a6bde?narHash=sha256-PXDZtnSSNXIlTlytspxkTm/RENaQKdTJ44RGqm/LPLA%3D' (2025-09-19)
• Updated input 'nixpkgs':
    'github:NixOS/nixpkgs/08b8f92ac6354983f5382124fef6006cade4a1c1?narHash=sha256-TjqVmbpoCqWywY9xIZLTf6ANFvDCXdctCjoYuYPYdMI%3D' (2025-09-16)
  → 'github:NixOS/nixpkgs/12bd230118a1901a4a5d393f9f56b6ad7e571d01?narHash=sha256-aBGl3XEOsjWw6W3AHiKibN7FeoG73dutQQEqnd/etR8%3D' (2025-09-19)

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

Author: github-actions[bot]