update readme to use magic-nix-cache action

.github/workflows/check-and-test.yaml

@@ -71,7 +71,7 @@ jobs:
         uses: DeterminateSystems/determinate-nix-action@v3
 
       - name: Test magic-nix-cache-action@main on ${{ matrix.systems.runner }}
-        uses: DeterminateSystems/flakehub-cache-action@main
+        uses: DeterminateSystems/magic-nix-cache-action@main
         with:
           source-binary: "${{ env.ARTIFACT_KEY }}/${{ env.ARCHIVE_NAME }}"
           _internal-strict-mode: true

README.md

@@ -11,8 +11,8 @@ permissions:
   id-token: write
 steps:
   - uses: actions/checkout@v4
-  - uses: DeterminateSystems/determinate-nix-action@v3
-  - uses: DeterminateSystems/flakehub-cache-action@main
+  - uses: DeterminateSystems/nix-installer-action@main
+  - uses: DeterminateSystems/magic-nix-cache-action@main
   - run: nix flake check
 ```
 
@@ -53,8 +53,8 @@ jobs:
       id-token: write
     steps:
       - uses: actions/checkout@v4
-      - uses: DeterminateSystems/determinate-nix-action@v3
-      - uses: DeterminateSystems/flakehub-cache-action@main
+      - uses: DeterminateSystems/nix-installer-action@main
+      - uses: DeterminateSystems/magic-nix-cache-action@main
       - run: nix flake check
 ```
 

magic-nix-cache/src/api.rs

@@ -1,6 +1,6 @@
 //! Action API.
 //!
-//! This API is intended to be used by determinate-nix-action.
+//! This API is intended to be used by nix-installer-action.
 
 use attic::nix_store::StorePath;
 use axum::{extract::Extension, routing::post, Json, Router};