build(deps): update nix requirement from 0.30 to 0.31 in the vhost group across 1 directory

[dependabot]

Updates the requirements on nix to permit the latest version.
Updates nix to 0.31.3

Changelog

Sourced from nix's changelog.

[0.31.3] - 2026-05-11

Added

• Enable module ioctl for Cygwin (#2715)
• Add CLOCK_BOOTTIME/CLOCK_PROCESS_CPUTIME_ID/CLOCK_THREAD_CPUTIME_ID/CLOCK_UPTIME to NetBSD-like platforms (#2716)
• unistd: add mkfifo for redox (#2749)
• Added kevent64 support on apple targets: Kqueue::kevent64, KEvent64, and Kevent64Flags. (#2781)

Fixed

• fix SaFlags_t definition on redox (#2751)
• Fixed EpollEvent::events() to use from_bits_retain instead of from_bits().unwrap(), preventing panics when the kernel returns unknown epoll flags. (#2783)
• Fixed KEvent::flags() and KEvent::fflags() to use from_bits_retain instead of from_bits().unwrap(), preventing panics when the kernel returns unknown kqueue flags. (#2784)

[0.31.2] - 2026-02-28

Added

• Add WatchDescriptor::as_raw, to get libc id of WatchDescriptor. (#2718)
• Added process::pthread_getthreadid_np() on FreeBSD. (#2725)
• Added timerfd support on FreeBSD (#2728)

Fixed

• The libc requirement is now 0.2.181, rather than pinned to 0.2.180. (#2744)

[0.31.1] - 2026-01-23

Added

• termios: Add definition for IUCLC to supported platforms (#2702)

... (truncated)

Commits

• b5933ca chore: release v0.31.3
• 5d6a46e Replace Cirrus CI with more Github Workflows jobs (#2776)
• 3407489 event: add kevent64 support on apple targets (#2781)
• fe80fc5 chore: resolve clippy useless_borrows_in_formatting (#2790)
• 3310fc7 Revert "fix(ci): temporarily disable armv7-unknown-linux-uclibceabihf (#2764)...
• e3ab917 epoll: use from_bits_retain to avoid panics on unknown flags (#2783)
• 6c15701 kqueue: use from_bits_retain to avoid panics on unknown flags (#2784)
• 73028cf fix(ci): enable Hurd target (#2765)
• 1a680a9 cargo: Remove deprecated package authors field (#2789)
• 85cff07 docs: add missing changelog entries (#2786)
• Additional commits viewable in compare view