workflows: add actionlint workflow

Co-authored-by: Bo Anderson <mail@boanderson.me>

.github/actionlint-matcher.json

@@ -0,0 +1,17 @@
+{
+  "problemMatcher": [
+    {
+      "owner": "actionlint",
+      "pattern": [
+        {
+          "regexp": "^(?:\\x1b\\[\\d+m)?(.+?)(?:\\x1b\\[\\d+m)*:(?:\\x1b\\[\\d+m)*(\\d+)(?:\\x1b\\[\\d+m)*:(?:\\x1b\\[\\d+m)*(\\d+)(?:\\x1b\\[\\d+m)*: (?:\\x1b\\[\\d+m)*(.+?)(?:\\x1b\\[\\d+m)* \\[(.+?)\\]$",
+          "file": 1,
+          "line": 2,
+          "column": 3,
+          "message": 4,
+          "code": 5
+        }
+      ]
+    }
+  ]
+}

.github/actionlint.yaml

@@ -0,0 +1,8 @@
+self-hosted-runner:
+  # Labels of self-hosted runner in array of strings.
+  labels:
+    - 11-arm64
+# Configuration variables in array of strings defined in your repository or
+# organization. `null` means disabling configuration variables check.
+# Empty array means no configuration variable is allowed.
+config-variables: []

.github/workflows/actionlint.yml

@@ -0,0 +1,47 @@
+name: actionlint
+
+on:
+  push:
+    branches:
+      - master
+    paths:
+      - '.github/workflows/*.ya?ml'
+  pull_request:
+    paths:
+      - '.github/workflows/*.ya?ml'
+  merge_group:
+
+env:
+  HOMEBREW_DEVELOPER: 1
+  HOMEBREW_NO_AUTO_UPDATE: 1
+  HOMEBREW_NO_ENV_HINTS: 1
+
+concurrency:
+  group: "actionlint-${{ github.ref }}"
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
+jobs:
+  workflow_syntax:
+    if: github.repository_owner == 'Homebrew'
+    runs-on: ubuntu-22.04
+    steps:
+      - name: Set up Homebrew
+        id: setup-homebrew
+        uses: Homebrew/actions/setup-homebrew@master
+        with:
+          test-bot: false
+
+      - name: Set up actionlint
+        env:
+          HOMEBREW_REPOSITORY: ${{ steps.setup-homebrew.outputs.repository-path }}
+        run: |
+          brew install actionlint shellcheck
+
+          # Annotations work only relative to GITHUB_WORKSPACE
+          (shopt -s dotglob; rm -rf "${GITHUB_WORKSPACE:?}"/*; mv "${HOMEBREW_REPOSITORY:?}"/* "$GITHUB_WORKSPACE")
+          rmdir "$HOMEBREW_REPOSITORY"
+          ln -vs "$GITHUB_WORKSPACE" "$HOMEBREW_REPOSITORY"
+
+          echo "::add-matcher::.github/actionlint-matcher.json"
+
+      - run: actionlint