ci: bump github-script, cache and setup-qemu actions to latest majors (#5778)

Update the GitHub Actions that had newer major versions available; all
other actions in the workflows were already pinned to their latest major
tag.

- actions/github-script: v7 -> v9
- actions/cache: v5 -> v6
- docker/setup-qemu-action: v3 -> v4

.github/workflows/download-link-on-pr.yml

@@ -8,7 +8,7 @@ jobs:
     if: github.event.workflow_run.event == 'pull_request' && github.event.workflow_run.conclusion == 'success'
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/github-script@v7
+      - uses: actions/github-script@v9
         with:
           # This snippet is public-domain, taken from
           # https://github.com/oprypin/nightly.link/blob/master/.github/workflows/pr-comment.yml

.github/workflows/pipeline.yml

@@ -166,7 +166,7 @@ jobs:
 
       - name: Cache ffmpeg
         id: ffmpeg-cache
-        uses: actions/cache@v5
+        uses: actions/cache@v6
         with:
           path: C:\ffmpeg
           key: ffmpeg-${{ env.FFMPEG_VERSION }}-win64
@@ -323,7 +323,7 @@ jobs:
 
       - name: Set up QEMU for smoke test
         if: env.IS_LINUX == 'true'
-        uses: docker/setup-qemu-action@v3
+        uses: docker/setup-qemu-action@v4
 
       # The binary is static, so binfmt+qemu runs it directly on the runner.
       # Catches startup crashes in cross-compiled binaries before they ship,