ci: add Node 20 to test and build matrix

Author: lxcario

.github/workflows/ci.yml

@@ -43,15 +43,18 @@ jobs:
       - run: npm run typecheck
 
   test:
-    name: Unit Tests
+    name: Unit Tests (Node ${{ matrix.node-version }})
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [20, 22]
     steps:
       - uses: actions/checkout@v5
 
       - name: Setup Node.js
         uses: actions/setup-node@v5
         with:
-          node-version: 22
+          node-version: ${{ matrix.node-version }}
           cache: 'npm'
 
       - run: npm ci
@@ -60,15 +63,18 @@ jobs:
           CI: true
 
   build:
-    name: Build
+    name: Build (Node ${{ matrix.node-version }})
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [20, 22]
     steps:
       - uses: actions/checkout@v5
 
       - name: Setup Node.js
         uses: actions/setup-node@v5
         with:
-          node-version: 22
+          node-version: ${{ matrix.node-version }}
           cache: 'npm'
 
       - run: npm ci