Run coveralls only for lts (#556)

Coveralls is having issues because we're sending data for both node 16.x
and lts. We only need to send data for one of them so let's split up the
builds

Author: k2snowman69

.github/workflows/ci.yml

@@ -37,12 +37,39 @@ jobs:
       - name: Test
         run: npm test
 
+  back-compat-oldest-node:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: [16.x]
+        # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
+
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+          cache: "npm"
+
+      - name: Install
+        run: npm ci --ignore-scripts
+
+      - name: Build
+        run: npm run build --if-present
+
+      - name: Test
+        run: npm test
+
   build:
     runs-on: ubuntu-latest
 
     strategy:
       matrix:
-        node-version: [16.x, lts/*]
+        node-version: [lts/*]
         # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
 
     steps: