Update weekly workflow (#488)

- Checkout repository.
- Install Node.js explicitly (to make sure the right version is
  installed).
- Pre-install dependencies.

Followup to d4589a7

.github/workflows/weekly.yml

@@ -18,12 +18,21 @@ jobs:
         uses: step-security/harden-runner@55d479fb1c5bcad5a4f9099a5d9f37c8857b2845 # v2.4.1
         with:
           egress-policy: audit
+      - name: Checkout repository
+        uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3
+      - name: Install Node.js
+        uses: actions/setup-node@64ed1c7eab4cce3362f8c340dee64e5eaeef8f7c # v3.6.0
+        with:
+          cache: npm
+          node-version-file: .nvmrc
       - name: Create automation token
         uses: tibdex/github-app-token@b62528385c34dbc9f38e5f4225ac829252d1ea92 # v1.8.0
         id: automation-token
         with:
           app_id: ${{ secrets.AUTOMATION_APP_ID }}
           private_key: ${{ secrets.AUTOMATION_APP_PRIVATE_KEY }}
+      - name: Install dependencies
+        run: npm clean-install
       - name: Update dependencies
         run: npm update
       - name: Dedupe dependencies