use nix caching and docker caching in CI

Also bumps tailscale version to trigger build and fixes a CLI test
that had the wrong capitalisation

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

.github/workflows/release.yml

@@ -16,7 +16,8 @@ jobs:
         with:
           fetch-depth: 0
 
-      - uses: cachix/install-nix-action@v16
+      - uses: DeterminateSystems/nix-installer-action@main
+      - uses: DeterminateSystems/magic-nix-cache-action@main
 
       - name: Run goreleaser
         run: nix develop --command -- goreleaser release --clean