Prevent cache poisoning vuln in GitHub Actions sample workflows

The PR #1917 bumped the
`actions/setup-node` action from v4 to v6. This made the publishing
GitHub Actions sample workflows potentially vulnerable to cache
poisoning, because v5 and later enable caching by default (see
https://github.com/actions/setup-node/blob/53b83947a5a98c8d113130e565377fae1a50d02f/README.md#breaking-changes-in-v5).
v6 only enables automatic caching if the `packageManager` field in
package.json is set to `npm`.

Consuming GitHub Actions cache in publishing workflows is discouraged,
because the cache may be poisoned by compromising any low-privileged
workflow in the same repository. Normally, a code injection
vulnerability in a low-privileged workflow (for example
`permissions: {contents: read}` and no secrets) is not a big deal,
because the attacker cannot do much more than poison the repository
cache (which requires no permissions). If caching is only used in other
low-privileged workflows, the impact is limited. However, if a
high-privileged workflow like the release build consumes the cache, then
it becomes a real problem.

As @AdnaneKhan concludes in his blog posts about GitHub Actions cache
poisoning, such as
https://adnanthekhan.com/2024/05/06/the-monsters-in-your-build-cache-github-actions-cache-poisoning/#dont-use-actions-caching-in-release-builds:
"the best way to protect the integrity of releases is to avoid using
GitHub Actions caching entirely for release workflows."

The README of `actions/setup-node` also recommends
`package-manager-cache: false` for privileged workflows (see
https://github.com/actions/setup-node/blob/53b83947a5a98c8d113130e565377fae1a50d02f/README.md#breaking-changes-in-v5):

> For workflows with elevated privileges or access to sensitive
> information, we recommend disabling automatic caching by setting
> `package-manager-cache: false` when caching is not needed for secure
> operation.

Author: generalmimon

content/packages-and-modules/securing-your-code/generating-provenance-statements.mdx

@@ -91,11 +91,12 @@ jobs:
       contents: read
       id-token: write
     steps:
-      - uses: actions/checkout@v4
-      - uses: actions/setup-node@v4
+      - uses: actions/checkout@v6
+      - uses: actions/setup-node@v6
         with:
-          node-version: '20.x'
+          node-version: '24.x'
           registry-url: 'https://registry.npmjs.org'
+          package-manager-cache: false  # never use caching in release builds
       - run: npm ci
       - run: npm publish --provenance --access public
         env:

content/packages-and-modules/securing-your-code/trusted-publishers.mdx

@@ -106,6 +106,7 @@ jobs:
         with:
           node-version: '24'
           registry-url: 'https://registry.npmjs.org'
+          package-manager-cache: false  # never use caching in release builds
       - run: npm ci
       - run: npm run build --if-present
       - run: npm test
@@ -298,10 +299,11 @@ While trusted publishing handles the publish operation, you may still need authe
 
 ```yaml
 # GitHub Actions example
-- uses: actions/setup-node@v4
+- uses: actions/setup-node@v6
   with:
     node-version: '24'
     registry-url: 'https://registry.npmjs.org'
+    package-manager-cache: false  # never use caching in release builds
 # Use a read-only token for installing dependencies
 - run: npm ci
   env: