Use project Go version for generating website content (arduino#167)

The project documentation is published on a companion website. A GitHub Actions workflow is used to automatically update
the website whenever any relevant file is changed in the repository. This website includes content generated from the
project's Go code.

Previously, the default version of Go from the GitHub Actions runner machine was used for generating the documentation
content. A recent update of this default Go version from 1.17 to 1.20 caused the generation process to fail:

```
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x83c1a6]

goroutine 1 [running]:
debug/elf.(*Section).ReadAt(0xc0001be000?, {0xc0001ce000?, 0x24?, 0x23?}, 0x23?)
	<autogenerated>:1 +0x26
archive/zip.readDirectoryEnd({0xa37480, 0xc0000af580}, 0x210)
	/opt/hostedtoolcache/go/1.20.3/x64/src/archive/zip/reader.go:581 +0xf5
archive/zip.(*Reader).init(0xc000137500, {0xa37480?, 0xc0000af580}, 0x210)
	/opt/hostedtoolcache/go/1.20.3/x64/src/archive/zip/reader.go:124 +0x5c
archive/zip.NewReader({0xa37480, 0xc0000af580}, 0x210)
	/opt/hostedtoolcache/go/1.20.3/x64/src/archive/zip/reader.go:103 +0x5e
github.com/daaku/go%2ezipexe.zipExeReaderElf({0xa38040?, 0xc0000140f0}, 0xdc51bf)
	/home/runner/go/pkg/mod/github.com/daaku/go.zipexe@v1.0.0/zipexe.go:128 +0x8b
github.com/daaku/go%2ezipexe.NewReader({0xa38040, 0xc0000140f0}, 0x0?)
	/home/runner/go/pkg/mod/github.com/daaku/go.zipexe@v1.0.0/zipexe.go:48 +0x98
github.com/daaku/go%2ezipexe.OpenCloser({0xc0000822a0?, 0xc0000e5720?})
	/home/runner/go/pkg/mod/github.com/daaku/go.zipexe@v1.0.0/zipexe.go:30 +0x57
github.com/cmaglie/go%2erice.init.0()
	/home/runner/go/pkg/mod/github.com/cmaglie/go.rice@v1.0.3/appended.go:42 +0x65
task: Failed to run task "go:cli-docs": exit status 2
```

This error, and the general fragility that comes from not controlling the Go version, is avoided by configuring the
workflow to use the specific version of Go that is used for development and validation of the project.

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-go/tree/main#supported-version-syntax
+  GO_VERSION: "1.18"
+
 # See: https://docs.github.com/en/actions/reference/events-that-trigger-workflows
 on:
   push:
@@ -56,6 +60,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v3
 
+      - name: Install Go
+        uses: actions/setup-go@v4
+        with:
+          go-version: ${{ env.GO_VERSION }}
+
       - name: Install Task
         uses: arduino/setup-task@v1
         with:

.github/workflows/deploy-cobra-mkdocs-versioned-poetry.yml

@@ -2,6 +2,8 @@
 name: Deploy Website
 
 env:
+  # See: https://github.com/actions/setup-go/tree/main#supported-version-syntax
+  GO_VERSION: "1.18"
   # See: https://github.com/actions/setup-python/tree/v2#available-versions-of-python
   PYTHON_VERSION: "3.9"
 
@@ -59,6 +61,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v3
 
+      - name: Install Go
+        uses: actions/setup-go@v4
+        with:
+          go-version: ${{ env.GO_VERSION }}
+
       - name: Install Python
         uses: actions/setup-python@v4
         with: