chore(deps): bump DeterminateSystems/nix-installer-action from 17 to 18

Bumps [DeterminateSystems/nix-installer-action](https://github.com/determinatesystems/nix-installer-action) from 17 to 18.
- [Release notes](https://github.com/determinatesystems/nix-installer-action/releases)
- [Commits](https://github.com/determinatesystems/nix-installer-action/compare/v17...v18)

---
updated-dependencies:
- dependency-name: DeterminateSystems/nix-installer-action
  dependency-version: '18'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/flake-checker.yml

@@ -16,6 +16,6 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
-      - uses: DeterminateSystems/nix-installer-action@v17
+      - uses: DeterminateSystems/nix-installer-action@v18
       - uses: DeterminateSystems/magic-nix-cache-action@v9
       - uses: DeterminateSystems/flake-checker-action@v10

.github/workflows/flake-updater.yml

@@ -13,7 +13,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0
-      - uses: DeterminateSystems/nix-installer-action@v17
+      - uses: DeterminateSystems/nix-installer-action@v18
       - uses: DeterminateSystems/magic-nix-cache-action@v9
       - uses: DeterminateSystems/update-flake-lock@v25
         with:

.github/workflows/test-build-quickemu.yml

@@ -53,7 +53,7 @@ jobs:
       - name: "Checkout 🥡"
         uses: "actions/checkout@v4"
       - name: "Install Nix ❄️"
-        uses: "DeterminateSystems/nix-installer-action@v17"
+        uses: "DeterminateSystems/nix-installer-action@v18"
       - name: "Enable Magic Nix Cache 🪄"
         uses: "DeterminateSystems/magic-nix-cache-action@v9"
       - name: "Build & Test .nix ❄️"