github: bump the github-dependencies group with 2 updates

Bumps the github-dependencies group with 2 updates: [DeterminateSystems/nix-installer-action](https://github.com/determinatesystems/nix-installer-action) and [DeterminateSystems/magic-nix-cache-action](https://github.com/determinatesystems/magic-nix-cache-action).


Updates `DeterminateSystems/nix-installer-action` from 13 to 14
- [Release notes](https://github.com/determinatesystems/nix-installer-action/releases)
- [Commits](DeterminateSystems/nix-installer-action@ab6bcb2...da36cb6)

Updates `DeterminateSystems/magic-nix-cache-action` from 7 to 8
- [Release notes](https://github.com/determinatesystems/magic-nix-cache-action/releases)
- [Commits](DeterminateSystems/magic-nix-cache-action@b46e247...87b14cf)

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

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

.github/workflows/build-nix.yml

@@ -22,6 +22,6 @@ jobs:
       - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332
         with:
           fetch-depth: 0
-      - uses: DeterminateSystems/nix-installer-action@ab6bcb2d5af0e904d04aea750e2089e9dc4cbfdd
-      - uses: DeterminateSystems/magic-nix-cache-action@b46e247b898aa56e6d2d2e728dc6df6c84fdb738
+      - uses: DeterminateSystems/nix-installer-action@da36cb69b1c3247ad7a1f931ebfd954a1105ef14
+      - uses: DeterminateSystems/magic-nix-cache-action@87b14cf437d03d37989d87f0fa5ce4f5dc1a330b
       - run: nix flake check -L --show-trace