chore(deps): bump DeterminateSystems/magic-nix-cache-action from 7 to 8

Bumps [DeterminateSystems/magic-nix-cache-action](https://github.com/determinatesystems/magic-nix-cache-action) from 7 to 8.
- [Release notes](https://github.com/determinatesystems/magic-nix-cache-action/releases)
- [Commits](https://github.com/determinatesystems/magic-nix-cache-action/compare/v7...v8)

---
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/flake-checker.yml

@@ -17,5 +17,5 @@ jobs:
         with:
           fetch-depth: 0
       - uses: DeterminateSystems/nix-installer-action@v14
-      - uses: DeterminateSystems/magic-nix-cache-action@v7
+      - uses: DeterminateSystems/magic-nix-cache-action@v8
       - uses: DeterminateSystems/flake-checker-action@v9

.github/workflows/flake-updater.yml

@@ -14,7 +14,7 @@ jobs:
         with:
           fetch-depth: 0
       - uses: DeterminateSystems/nix-installer-action@v14
-      - uses: DeterminateSystems/magic-nix-cache-action@v7
+      - uses: DeterminateSystems/magic-nix-cache-action@v8
       - uses: DeterminateSystems/update-flake-lock@v24
         with:
           pr-title: "chore: update flake.lock"

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

@@ -55,7 +55,7 @@ jobs:
       - name: "Install Nix ❄️"
         uses: "DeterminateSystems/nix-installer-action@v14"
       - name: "Enable Magic Nix Cache 🪄"
-        uses: "DeterminateSystems/magic-nix-cache-action@v7"
+        uses: "DeterminateSystems/magic-nix-cache-action@v8"
       - name: "Build & Test .nix ❄️"
         run: |
           nix build .#quickemu