ci: bump DeterminateSystems/nix-installer-action from 18 to 19

---
updated-dependencies:
- dependency-name: DeterminateSystems/nix-installer-action
  dependency-version: '19'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/check.yml

@@ -34,7 +34,7 @@ jobs:
         with:
           persist-credentials: false
 
-      - uses: DeterminateSystems/nix-installer-action@v18
+      - uses: DeterminateSystems/nix-installer-action@v19
 
       - uses: cachix/cachix-action@v16
         with:

.github/workflows/doc.yml

@@ -28,7 +28,7 @@ jobs:
         with:
           persist-credentials: false
 
-      - uses: DeterminateSystems/nix-installer-action@v18
+      - uses: DeterminateSystems/nix-installer-action@v19
 
       - uses: cachix/cachix-action@v16
         with:

.github/workflows/update-flake.yml

@@ -17,7 +17,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           ref: ${{ matrix.branch }}
-      - uses: DeterminateSystems/nix-installer-action@v18
+      - uses: DeterminateSystems/nix-installer-action@v19
 
       - id: generate-token
         uses: actions/create-github-app-token@v2