Merge bitcoin-core/secp256k1#1841: gha: Bump deprecated GHA workflow dependencies

c5cd9d6d9a gha: Bump deprecated GHA workflow dependencies (Tim Ruffing)

Pull request description:

  Deprecation notice:
  https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

  Changelogs (no entries relevant to us):
    * https://github.com/docker/setup-buildx-action/releases/tag/v4.0.0
    * https://github.com/docker/build-push-action/releases/tag/v7.0.0
    * https://github.com/actions/cache#v5

ACKs for top commit:
  hebasto:
    ACK c5cd9d6d9a.

Tree-SHA512: d21509503a617344f5f93a87fe229774e5ab5322ae2f322b38c7fdaef54ab3386a5eaa9901cb1b15f32c7891d2587aab709c70df9f5aaedc7524710496981311

.github/actions/install-homebrew-valgrind/action.yml

@@ -16,7 +16,7 @@ runs:
         cat valgrind_fingerprint
       shell: bash
 
-    - uses: actions/cache@v4
+    - uses: actions/cache@v5
       id: cache
       with:
         path: ${{ env.CI_HOMEBREW_CELLAR_VALGRIND }}

.github/actions/run-in-docker-action/action.yml

@@ -13,9 +13,9 @@ inputs:
 runs:
   using: "composite"
   steps:
-    - uses: docker/setup-buildx-action@v3
+    - uses: docker/setup-buildx-action@v4
 
-    - uses: docker/build-push-action@v6
+    - uses: docker/build-push-action@v7
       id: main_builder
       continue-on-error: true
       with:
@@ -24,7 +24,7 @@ runs:
         load: true
         cache-from: type=gha,scope=${{ inputs.scope }}
 
-    - uses: docker/build-push-action@v6
+    - uses: docker/build-push-action@v7
       id: retry_builder
       if: steps.main_builder.outcome == 'failure'
       with:

.github/workflows/ci.yml

@@ -73,14 +73,14 @@ jobs:
         run: echo "period=$((10#$(date +%V) / 4))" >> "$GITHUB_OUTPUT"
 
       - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@v4
         with:
           # See: https://github.com/moby/buildkit/issues/3969.
           driver-opts: |
             network=host
 
       - name: Build container
-        uses: docker/build-push-action@v6
+        uses: docker/build-push-action@v7
         with:
           file: ./ci/linux-debian.Dockerfile
           cache-from: type=gha,scope=${{ runner.arch }}-${{ steps.cache_timestamp.outputs.period }}