Update nixpkgs

[airportyh]

Why

Update to latest of nixpkgs 23.05 channel.

What changed

1. nix flake lock --update-input nixpkgs
2. Added linear auto upgrade entries

Test plan

Run template tests.

Rollout

Describe any procedures or requirements needed to roll this out safely (or check the box below)

• [x] This is fully backward and forward compatible

[airportyh]

One concern: glib/libgcc changed (not the semvar version but the nix version), so this will increase the disk size substantially.