Use workflow variables to define tool versions

Placement of this information at the top of the GitHub Actions workflow files, where it is easy to find and edit,
facilitates updates to the workflows as the tool versions used for project development are bumped periodically.

Author: per1234

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

@@ -1,5 +1,9 @@
 name: Check Go
 
+env:
+  # See: https://github.com/actions/setup-go/tree/v2#readme
+  GO_VERSION: "1.14"
+
 # See: https://docs.github.com/en/actions/reference/events-that-trigger-workflows
 on:
   push:
@@ -30,6 +34,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v2
 
+      - name: Install Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: ${{ env.GO_VERSION }}
+
       - name: Install Task
         uses: arduino/setup-task@v1
         with:
@@ -46,6 +55,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v2
 
+      - name: Install Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: ${{ env.GO_VERSION }}
+
       - name: Install Task
         uses: arduino/setup-task@v1
         with:
@@ -65,6 +79,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v2
 
+      - name: Install Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: ${{ env.GO_VERSION }}
+
       - name: Install Task
         uses: arduino/setup-task@v1
         with:
@@ -81,6 +100,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v2
 
+      - name: Install Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: ${{ env.GO_VERSION }}
+
       - name: Install Task
         uses: arduino/setup-task@v1
         with:
@@ -100,6 +124,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v2
 
+      - name: Install Go
+        uses: actions/setup-go@v2
+        with:
+          go-version: ${{ env.GO_VERSION }}
+
       - name: Run go mod tidy
         run: go mod tidy
 

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

@@ -1,5 +1,9 @@
 name: Check Python
 
+env:
+  # See: https://github.com/actions/setup-python/tree/v2#available-versions-of-python
+  PYTHON_VERSION: "3.9"
+
 # See: https://docs.github.com/en/actions/reference/events-that-trigger-workflows
 on:
   push:
@@ -36,7 +40,7 @@ jobs:
       - name: Install Python
         uses: actions/setup-python@v2
         with:
-          python-version: "3.9"
+          python-version: ${{ env.PYTHON_VERSION }}
 
       - name: Install Poetry
         run: pip install poetry
@@ -60,7 +64,7 @@ jobs:
       - name: Install Python
         uses: actions/setup-python@v2
         with:
-          python-version: "3.9"
+          python-version: ${{ env.PYTHON_VERSION }}
 
       - name: Install Poetry
         run: pip install poetry

.github/workflows/release.yml

@@ -1,5 +1,9 @@
 name: Create Release
 
+env:
+  # See: https://github.com/actions/setup-go/tree/v2#readme
+  GO_VERSION: "1.14"
+
 on:
   push:
     tags:
@@ -32,7 +36,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v2
         with:
-          go-version: "1.14"
+          go-version: ${{ env.GO_VERSION }}
 
       - name: Build project
         run: task build

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

@@ -1,5 +1,9 @@
 name: Spell Check
 
+env:
+  # See: https://github.com/actions/setup-python/tree/v2#available-versions-of-python
+  PYTHON_VERSION: "3.9"
+
 # See: https://docs.github.com/en/free-pro-team@latest/actions/reference/events-that-trigger-workflows
 on:
   push:
@@ -21,7 +25,7 @@ jobs:
       - name: Install Python
         uses: actions/setup-python@v2
         with:
-          python-version: "3.9"
+          python-version: ${{ env.PYTHON_VERSION }}
 
       - name: Install Poetry
         run: pip install poetry

.github/workflows/test-go-integration-task.yml

@@ -1,5 +1,11 @@
 name: Test Integration
 
+env:
+  # See: https://github.com/actions/setup-go/tree/v2#readme
+  GO_VERSION: "1.14"
+  # See: https://github.com/actions/setup-python/tree/v2#available-versions-of-python
+  PYTHON_VERSION: "3.9"
+
 # See: https://docs.github.com/en/free-pro-team@latest/actions/reference/events-that-trigger-workflows
 on:
   push:
@@ -46,12 +52,12 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v2
         with:
-          go-version: "1.14"
+          go-version: ${{ env.GO_VERSION }}
 
       - name: Install Python
         uses: actions/setup-python@v2
         with:
-          python-version: "3.9"
+          python-version: ${{ env.PYTHON_VERSION }}
 
       - name: Install Poetry
         run: pip install poetry

.github/workflows/test-go-task.yml

@@ -1,5 +1,9 @@
 name: Test Go
 
+env:
+  # See: https://github.com/actions/setup-go/tree/v2#readme
+  GO_VERSION: "1.14"
+
 # See: https://docs.github.com/en/free-pro-team@latest/actions/reference/events-that-trigger-workflows
 on:
   push:
@@ -32,7 +36,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v2
         with:
-          go-version: "1.14"
+          go-version: ${{ env.GO_VERSION }}
 
       - name: Install Taskfile
         uses: arduino/setup-task@v1
@@ -60,7 +64,7 @@ jobs:
       - name: Install Go
         uses: actions/setup-go@v2
         with:
-          go-version: "1.14"
+          go-version: ${{ env.GO_VERSION }}
 
       - name: Install Arduino Lint
         run: |