chore(ci): Drop matrix for lint job (#2477)

Fixes #2283

In order to avoid unnecessary duplication of effort in CI and to keep
the required Lint job name consistent as we upgrade the underlying
Node.js version, this change drops the test matrix and hard-codes the
platform and node version.

.github/workflows/ci.yml

@@ -19,12 +19,9 @@ jobs:
 
     # begin macro
 
-    runs-on: ${{ matrix.platform }}
+    runs-on: ubuntu-latest
     strategy:
       fail-fast: false
-      matrix:
-        node-version: [18.x, 20.x]
-        platform: [ubuntu-latest]
 
     steps:
       - name: Checkout
@@ -33,10 +30,10 @@ jobs:
       # without this, setup-node errors on mismatched yarn versions
       - run: corepack enable
 
-      - name: Use Node.js ${{ matrix.node-version }}
+      - name: Use Node.js
         uses: actions/setup-node@v3
         with:
-          node-version: ${{ matrix.node-version }}
+          node-version: 20.x
           cache: yarn
 
       - name: Install dependencies