chore(3p): bump NixOS unstable channel to 2021-09-30 r/2939

depot-nixpkgs-update did not update the unstable channel properly, since
nixos.org still has caching issues: The channel has updated (e. g. the
nixos-unstable branch in nixpkgs), but channels.nixos.org is still
pointing to a stale version. See:

* https://github.com/NixOS/nixpkgs/issues/140026
* https://github.com/NixOS/nixos-org-configurations/issues/169

I've updated the channel manually here, since that version of nixpkgs
has a fix for bqn-mode I'm interested in.

Hopefully this problem is sorted out soon since depot-nixpkgs-update
relies on the HTTP channel “API” to obtain the date of the channel (as
opposed to the date of the commit).

Change-Id: Iae55e4a7f77b479e08dbe9eb82752ecc4f470d81
Reviewed-on: https://cl.tvl.fyi/c/depot/+/3656
Tested-by: BuildkiteCI
Reviewed-by: tazjin <mail@tazj.in>

0 files changed, 0 insertions, 0 deletions