Control Node.js version used in relevant GitHub Actions workflows

The GitHub Actions workflows have tool dependencies sourced from npm.

Previously, the workflows were not configured to set up a specific version of Node.js, which caused the default version
from the GitHub Actions runner to be used. That version might be changed at any time, which left the workflows
vulnerable to breakage.

Setting a specific version of Node.js provides stability. Updates to the version can be made in a controlled manner,
with validation before the workflow goes into production use.

The version is set via an environment variable at the top of the workflow in order to facilitate updates.

Author: per1234

.github/workflows/check-markdown-task.yml

@@ -1,6 +1,10 @@
 # Source: https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/check-markdown-task.md
 name: Check Markdown
 
+env:
+  # See: https://github.com/actions/setup-node/#readme
+  NODE_VERSION: 16.x
+
 # See: https://docs.github.com/en/actions/reference/events-that-trigger-workflows
 on:
   push:
@@ -37,6 +41,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v2
 
+      - name: Setup Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+
       - name: Initialize markdownlint-cli problem matcher
         uses: xt0rted/markdownlint-problem-matcher@v1
 
@@ -56,6 +65,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v2
 
+      - name: Setup Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+
       - name: Install Task
         uses: arduino/setup-task@v1
         with:

.github/workflows/check-prettier-formatting-task.yml

@@ -1,6 +1,10 @@
 # Source: https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/check-prettier-formatting-task.md
 name: Check Prettier Formatting
 
+env:
+  # See: https://github.com/actions/setup-node/#readme
+  NODE_VERSION: 16.x
+
 # See: https://docs.github.com/en/free-pro-team@latest/actions/reference/events-that-trigger-workflows
 on:
   push:
@@ -206,6 +210,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v2
 
+      - name: Setup Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+
       - name: Install Task
         uses: arduino/setup-task@v1
         with:

.github/workflows/check-taskfiles.yml

@@ -1,6 +1,10 @@
 # Source: https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/check-taskfiles.md
 name: Check Taskfiles
 
+env:
+  # See: https://github.com/actions/setup-node/#readme
+  NODE_VERSION: 16.x
+
 # See: https://docs.github.com/en/actions/reference/events-that-trigger-workflows
 on:
   push:
@@ -37,6 +41,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v2
 
+      - name: Setup Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+
       - name: Download JSON schema for Taskfiles
         id: download-schema
         uses: carlosperate/download-file-action@v1

.github/workflows/check-workflows-task.yml

@@ -1,6 +1,10 @@
 # Source: https://github.com/arduino/tooling-project-assets/blob/master/workflow-templates/check-workflows-task.md
 name: Check Workflows
 
+env:
+  # See: https://github.com/actions/setup-node/#readme
+  NODE_VERSION: 16.x
+
 # See: https://docs.github.com/en/actions/reference/events-that-trigger-workflows
 on:
   push:
@@ -25,6 +29,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v2
 
+      - name: Setup Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+
       - name: Install Task
         uses: arduino/setup-task@v1
         with:

.github/workflows/sync-labels.yml

@@ -1,6 +1,12 @@
 # Source: https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/sync-labels.md
 name: Sync Labels
 
+env:
+  # See: https://github.com/actions/setup-node/#readme
+  NODE_VERSION: 16.x
+  CONFIGURATIONS_FOLDER: .github/label-configuration-files
+  CONFIGURATIONS_ARTIFACT: label-configuration-files
+
 # See: https://docs.github.com/en/actions/reference/events-that-trigger-workflows
 on:
   push:
@@ -17,10 +23,6 @@ on:
   workflow_dispatch:
   repository_dispatch:
 
-env:
-  CONFIGURATIONS_FOLDER: .github/label-configuration-files
-  CONFIGURATIONS_ARTIFACT: label-configuration-files
-
 jobs:
   check:
     runs-on: ubuntu-latest
@@ -29,6 +31,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v2
 
+      - name: Setup Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+
       - name: Download JSON schema for labels configuration file
         id: download-schema
         uses: carlosperate/download-file-action@v1
@@ -118,6 +125,11 @@ jobs:
         with:
           name: ${{ env.CONFIGURATIONS_ARTIFACT }}
 
+      - name: Setup Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+
       - name: Merge label configuration files
         run: |
           # Merge all configuration files