Release v3.15.1 (#1735)

* Prepare release v3.15.1

* Update test fixtures with the new nix-installer version

* flake.lock: Update

Flake lock file updates:

• Updated input 'determinate':
    'https://api.flakehub.com/f/pinned/DeterminateSystems/determinate/3.15.0/019b3865-57a1-7d80-98c5-962fac29c404/source.tar.gz' (2025-12-19)
  → 'https://api.flakehub.com/f/pinned/DeterminateSystems/determinate/3.15.1/019b4e8a-dc22-75db-aef5-a447efbb1a13/source.tar.gz' (2025-12-24)
• Updated input 'determinate/determinate-nixd-aarch64-darwin':
    'https://install.determinate.systems/determinate-nixd/tag/v3.15.0/macOS'
  → 'https://install.determinate.systems/determinate-nixd/tag/v3.15.1/macOS'
• Updated input 'determinate/determinate-nixd-aarch64-linux':
    'https://install.determinate.systems/determinate-nixd/tag/v3.15.0/aarch64-linux'
  → 'https://install.determinate.systems/determinate-nixd/tag/v3.15.1/aarch64-linux'
• Updated input 'determinate/determinate-nixd-x86_64-linux':
    'https://install.determinate.systems/determinate-nixd/tag/v3.15.0/x86_64-linux'
  → 'https://install.determinate.systems/determinate-nixd/tag/v3.15.1/x86_64-linux'
• Updated input 'nix':
    'https://api.flakehub.com/f/pinned/DeterminateSystems/nix-src/3.15.0/019b3854-cca6-7298-a91c-0fd8551a7270/source.tar.gz' (2025-12-19)
  → 'https://api.flakehub.com/f/pinned/DeterminateSystems/nix-src/3.15.1/019b4e84-d036-75db-b6c6-6bc2e2035c53/source.tar.gz' (2025-12-24)
• Updated input 'nixpkgs':
    'https://api.flakehub.com/f/pinned/NixOS/nixpkgs/0.1.912002%2Brev-1306659b587dc277866c7b69eb97e5f07864d8c4/019b2463-7b8e-7042-8b7e-490d08a3cd7a/source.tar.gz' (2025-12-15)
  → 'https://api.flakehub.com/f/pinned/NixOS/nixpkgs/0.1.914755%2Brev-a6531044f6d0bef691ea18d4d4ce44d0daa6e816/019b4613-7276-7c80-8e57-953e4698fb6e/source.tar.gz' (2025-12-21)

* Update Cargo dependencies

* Set Cargo.toml package.version to 3.15.1

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: github-actions[bot]

Cargo.lock

@@ -1,7 +1,7 @@
 [package]
 name = "nix-installer"
 description = "The Determinate Nix Installer"
-version = "3.15.0"
+version = "3.15.1"
 edition = "2021"
 resolver = "2"
 license = "LGPL-2.1"

Cargo.toml

@@ -1,5 +1,5 @@
 {
-  "version": "3.15.0",
+  "version": "3.15.1",
   "actions": [
     {
       "action": {

flake.lock

@@ -1,5 +1,5 @@
 {
-  "version": "3.15.0",
+  "version": "3.15.1",
   "actions": [
     {
       "action": {

tests/fixtures/linux/linux.json

@@ -1,5 +1,5 @@
 {
-  "version": "3.15.0",
+  "version": "3.15.1",
   "actions": [
     {
       "action": {