Update README.md and action.yml for v3.15.0

Author: github-actions[bot]

README.md

@@ -49,9 +49,9 @@ jobs:
       id-token: "write"
       contents: "read"
     steps:
-      - uses: actions/[email protected].0
+      - uses: actions/[email protected].1
       - uses: DeterminateSystems/determinate-nix-action@v3
-      - uses: DeterminateSystems/flakehub-cache-action@v2 # or v2.2.0 to pin to a release
+      - uses: DeterminateSystems/flakehub-cache-action@v3 # or v3.15.0 to pin to a release
       - run: nix build .
 ```
 
@@ -65,7 +65,7 @@ jobs:
 Unlike `DeterminateSystems/magic-nix-cache-action`, we fully support explicit version pinning for maximum consistency.
 This Action is **automatically tagged** for every release, giving you complete control over your CI environment:
 
-📍 Pinning to `DeterminateSystems/flakehub-cache-action@v2.2.0` guarantees:
+📍 Pinning to `DeterminateSystems/flakehub-cache-action@v3.15.0` guarantees:
 
 - Same `flakehub-cache-action` revision every time
 - Reproducible CI workflows, even years later
@@ -109,7 +109,7 @@ Set to "disabled" or false to explicitly disable the GitHub Actions Cache.
 | `source-binary`             | Run a version of the cache binary from somewhere already on disk. Conflicts with all other `source-*` options.                                                                                                                                                                                                                                               |          |                                            |
 | `source-branch`             | The branch of `magic-nix-cache` to use. Conflicts with all other `source-*` options.                                                                                                                                                                                                                                                                         |          |                                            |
 | `source-pr`                 | The PR of `magic-nix-cache` to use. Conflicts with all other `source-*` options.                                                                                                                                                                                                                                                                             |          |                                            |
-| `source-revision`           | The revision of `nix-magic-nix-cache` to use. Conflicts with all other `source-*` options.                                                                                                                                                                                                                                                                   |          | `6d0587612b1cebc534c1e8840f2468d9b0ec6ed0` |
+| `source-revision`           | The revision of `nix-magic-nix-cache` to use. Conflicts with all other `source-*` options.                                                                                                                                                                                                                                                                   |          | `4b5df5f2f2393f10fc346297a46deec91a5969e0` |
 | `source-tag`                | The tag of `magic-nix-cache` to use. Conflicts with all other `source-*` options.                                                                                                                                                                                                                                                                            |          |                                            |
 | `source-url`                | A URL pointing to a `magic-nix-cache` binary. Overrides all other `source-*` options.                                                                                                                                                                                                                                                                        |          |                                            |
 | `flakehub-cache-server`     | The FlakeHub binary cache server.                                                                                                                                                                                                                                                                                                                            |          | `https://cache.flakehub.com`               |

action.yml

@@ -52,7 +52,7 @@
         "source-revision": {
             "description": "The revision of `nix-magic-nix-cache` to use. Conflicts with all other `source-*` options.",
             "required": false,
-            "default": "6d0587612b1cebc534c1e8840f2468d9b0ec6ed0"
+            "default": "4b5df5f2f2393f10fc346297a46deec91a5969e0"
         },
         "source-tag": {
             "description": "The tag of `magic-nix-cache` to use. Conflicts with all other `source-*` options.",
@@ -80,7 +80,7 @@
         "using": "composite",
         "steps": [
             {
-                "uses": "DeterminateSystems/magic-nix-cache-action@c6a5746789488c8753af0d61fc6b5d79a80391f3",
+                "uses": "DeterminateSystems/magic-nix-cache-action@b8276522d77f21bf19d3574e5bc99186a6c7aa6c",
                 "with": {
                     "use-gha-cache": "${{ inputs.use-gha-cache }}",
                     "flakehub-flake-name": "${{ inputs.flakehub-flake-name }}",