test: Run CI on first and last of each stable version.

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v2
         with:
-          node-version: 14.x
+          node-version: '14.x'
       - run: npm ci --ignore-scripts
       - run: npm run lint
 
@@ -26,8 +26,10 @@ jobs:
     strategy:
       matrix:
         node-version:
-          - 12.x
-          - 14.x
+          - '12.17'
+          - '12.x'
+          - '14.0'
+          - '14.x'
     env:
       TEST_DOCKER: true
     services:
@@ -70,8 +72,8 @@ jobs:
     strategy:
       matrix:
         node-version:
-          - 12.x
-          - 14.x
+          - '12.x'
+          - '14.x'
     steps:
       - name: Use Node.js ${{ matrix.node-version }}
         uses: actions/setup-node@v2
@@ -108,7 +110,7 @@ jobs:
       - uses: actions/checkout@v2
       - uses: actions/setup-node@v2
         with:
-          node-version: 14.x
+          node-version: '14.x'
       - run: npm ci --ignore-scripts
       - run: npm run docs
       - name: Save docs