chore: renovate bot setting to pin actions to a full length commit SHA (#2613)

- https://docs.renovatebot.com/modules/manager/github-actions/#additional-information
- Pinned actions by SHA https://github.com/ossf/scorecard/blob/main/docs/checks.md#pinned-dependencies

>Pin actions to a full length commit SHA

>Pinning an action to a full length commit SHA is currently the only way to use an action as an immutable release.
> Pinning to a particular SHA helps mitigate the risk of a bad actor adding a backdoor to the action's repository,
> as they would need to generate a SHA-1 collision for a valid Git object payload.

- https://docs.github.com/en/actions/security-guides/security-hardening-for-github-actions#using-third-party-actions
- https://github.com/renovatebot/.github/blob/b0c3aa85ef2bb242580f20b02b380ca532b4ce17/default.json#L13

Author: naveensrinivasan

renovate.json

@@ -1,6 +1,7 @@
 {
   "extends": [
-    "config:base"
+    "config:base",
+    "helpers:pinGitHubActionDigests"
   ],
   "baseBranches": ["release/4.1.x", "release/4.2.x", "release/5.0.x"],
   "dependencyDashboard": true,