403 response when packages are fetch‍ed from Nix builds

### Current Behavior Nix builds that were recently working fine are failing with an unexplained 403 error while downloading crates. ### Expected Behavior Nix builds should be able to download crates instead of randomly breaking. ### Steps To Reproduce `nix build github:jj-vcs/jj` and observe failures ### Environment - Browser: N/A - OS: NixOS 26.05 (Yarara) x86_64 — Linux 6.18.24 ### Anything else? https://files.pool.net.eu.org/-/6eer5nuecorg/afhw4xm8kky1v06rr3c40dz14742fw-crate-shlex-2.0.1.tar.gz.drv.bz2