.github/pr-triage: update node.js to v16

[Warning](https://github.com/ceph/ceph/actions/runs/3273201887):
```
Node.js 12 actions are deprecated. For more information see: https://github.blog/changelog/2022-09-22-github-actions-all-actions-will-begin-running-on-node16-instead-of-node12/.
Please update the following actions to use Node.js 16: actions/labeler, iyu/actions-milestone
```

Signed-off-by: Ernesto Puerta <37327689+epuertat@users.noreply.github.com>

.github/workflows/pr-triage.yml

@@ -8,7 +8,8 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Assign labels based on modified files
-        uses: actions/labeler@9794b1493b6f1fa7b006c5f8635a19c76c98be95
+        # https://github.com/marketplace/actions/labeler?version=v4.0.2
+        uses: actions/labeler@5c7539237e04b714afd8ad9b4aed733815b9fab4
         with:
           sync-labels: ''
           repo-token: "${{ secrets.GITHUB_TOKEN }}"
@@ -20,7 +21,8 @@ jobs:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           labeled: dashboard
       - name: Assign milestone based on target brach name
-        uses: iyu/actions-milestone@dbf7e5348844c9ddc6b803a5721b85fa70fe3bb9
+        # https://github.com/marketplace/actions/pull-request-milestone?version=v1.3.0
+        uses: iyu/actions-milestone@e93115c90ff7bcddee71086e9253f1b6a5f4b48a
         with:
           configuration-path: .github/milestone.yml
           repo-token: "${{ secrets.GITHUB_TOKEN }}"