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

Signed-off-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/blockchain.yml

@@ -73,7 +73,7 @@ jobs:
         ref: ${{ env.MONOREPO_COMMIT }}
     - name: Conditionally setup Node.js
       if: steps.celo-monorepo-cache.outputs.cache-hit != 'true'
-      uses: actions/setup-node@v4
+      uses: actions/setup-node@v6
       with:
         node-version: ${{ env.NODE_VERSION }}
         cache: yarn
@@ -425,7 +425,7 @@ jobs:
         restore-keys: |
           celo-monorepo-cache-
     - name: Setup Node.js
-      uses: actions/setup-node@v4
+      uses: actions/setup-node@v6
       with:
         node-version: ${{ env.NODE_VERSION }}
         cache: yarn
@@ -474,7 +474,7 @@ jobs:
         restore-keys: |
           celo-monorepo-cache-
     - name: Setup Node.js
-      uses: actions/setup-node@v4
+      uses: actions/setup-node@v6
       with:
         node-version: ${{ env.NODE_VERSION }}
         cache: yarn
@@ -523,7 +523,7 @@ jobs:
         restore-keys: |
           celo-monorepo-cache-
     - name: Setup Node.js
-      uses: actions/setup-node@v4
+      uses: actions/setup-node@v6
       with:
         node-version: ${{ env.NODE_VERSION }}
         cache: yarn
@@ -571,7 +571,7 @@ jobs:
         restore-keys: |
           celo-monorepo-cache-
     - name: Setup Node.js
-      uses: actions/setup-node@v4
+      uses: actions/setup-node@v6
       with:
         node-version: ${{ env.NODE_VERSION }}
         cache: yarn
@@ -619,7 +619,7 @@ jobs:
         restore-keys: |
           celo-monorepo-cache-
     - name: Setup Node.js
-      uses: actions/setup-node@v4
+      uses: actions/setup-node@v6
       with:
         node-version: ${{ env.NODE_VERSION }}
         cache: yarn
@@ -667,7 +667,7 @@ jobs:
         restore-keys: |
           celo-monorepo-cache-
     - name: Setup Node.js
-      uses: actions/setup-node@v4
+      uses: actions/setup-node@v6
       with:
         node-version: ${{ env.NODE_VERSION }}
         cache: yarn
@@ -715,7 +715,7 @@ jobs:
         restore-keys: |
           celo-monorepo-cache-
     - name: Setup Node.js
-      uses: actions/setup-node@v4
+      uses: actions/setup-node@v6
       with:
         node-version: ${{ env.NODE_VERSION }}
         cache: yarn
@@ -763,7 +763,7 @@ jobs:
         restore-keys: |
           celo-monorepo-cache-
     - name: Setup Node.js
-      uses: actions/setup-node@v4
+      uses: actions/setup-node@v6
       with:
         node-version: ${{ env.NODE_VERSION }}
         cache: yarn