chore(deps): update actions/setup-node action to v6

Author: renovate[bot]

.github/workflows/build.yml

@@ -18,7 +18,7 @@ jobs:
       # set up correct version of node
       - id: nvmrc
         run: echo ::set-output name=NODE_VERSION::$(cat ../../.nvmrc)
-      - uses: actions/setup-node@v2
+      - uses: actions/setup-node@v6
         with: { node-version: '${{ steps.nvmrc.outputs.NODE_VERSION }}' }
 
       - run: yarn

.github/workflows/lighthouse.yml

@@ -14,7 +14,7 @@ jobs:
       # set up correct version of node
       - id: nvmrc
         run: echo ::set-output name=NODE_VERSION::$(cat .nvmrc)
-      - uses: actions/setup-node@v2
+      - uses: actions/setup-node@v6
         with: { node-version: '${{ steps.nvmrc.outputs.NODE_VERSION }}' }
 
       - name: Install dependencies