build(deps): Bump DeterminateSystems/nix-installer-action from 9 to 12

Bumps [DeterminateSystems/nix-installer-action](https://github.com/determinatesystems/nix-installer-action) from 9 to 12.
- [Release notes](https://github.com/determinatesystems/nix-installer-action/releases)
- [Commits](DeterminateSystems/nix-installer-action@v9...v12)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/update.yml

@@ -15,7 +15,7 @@ jobs:
       contents: write
     steps:
       - uses: actions/checkout@v4
-      - uses: DeterminateSystems/nix-installer-action@v9
+      - uses: DeterminateSystems/nix-installer-action@v12
       - uses: DeterminateSystems/update-flake-lock@v20
         with:
           pr-title: "chore: update flake.lock"