chore: Convert spellcheck to GitHub Action

.github/workflows/cspell-problem-matcher.json

@@ -0,0 +1,16 @@
+{
+  "problemMatcher": [
+    {
+      "owner": "cspell",
+      "pattern": [
+        {
+          "regexp": "^(.*):(\\d+):(\\d+)\\s+\\-\\s+(.*)$",
+          "file": 1,
+          "line": 2,
+          "column": 3,
+          "message": 4
+        }
+      ]
+    }
+  ]
+}

.github/workflows/spelling.yml

@@ -0,0 +1,39 @@
+name: Spellcheck
+
+on:
+  push:
+    paths:
+      - "package*.json"
+      - "cspell.json"
+      - "aria-practices.html"
+      - "examples/**/*.html"
+      - ".github/workflows/cspell-problem-matcher.json"
+      - ".github/workflows/spelling.yml"
+
+  pull_request:
+    paths:
+      - "package*.json"
+      - "cspell.json"
+      - "aria-practices.html"
+      - "examples/**/*.html"
+      - ".github/workflows/cspell-problem-matcher.json"
+      - ".github/workflows/spelling.yml"
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Clone repository
+        uses: actions/checkout@v2
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v2.1.1
+
+      - name: Install npm dependencies
+        run: npm ci
+
+      - name: cSpell
+        run: |
+          echo "::add-matcher::.github/workflows/cspell-problem-matcher.json"
+          npm run lint:spelling

.travis.yml

@@ -10,15 +10,8 @@ stages:
 - Lint
 
 jobs:
-  fast_finish: true
-  allow_failures:
-    - env: ALLOW_FAILURE=true
 
   include:
     - stage: Lint
       name: HTML Linting
       script: npm run vnu-jar
-    - stage: Lint
-      name: Spellcheck
-      script: npm run lint:spelling
-      env: ALLOW_FAILURE=true