Bump DeterminateSystems/magic-nix-cache-action from 3 to 4

Bumps [DeterminateSystems/magic-nix-cache-action](https://github.com/determinatesystems/magic-nix-cache-action) from 3 to 4.
- [Release notes](https://github.com/determinatesystems/magic-nix-cache-action/releases)
- [Commits](DeterminateSystems/magic-nix-cache-action@v3...v4)

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

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

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
         with:
           name: nix-community
       - name: Setup nix cache
-        uses: DeterminateSystems/magic-nix-cache-action@v3
+        uses: DeterminateSystems/magic-nix-cache-action@v4
       - name: Setup go cache
         uses: actions/setup-go@v5
         with: