Update CI workflow to include main branch

Author: austenstone

.github/workflows/ci.yml

@@ -3,22 +3,21 @@ on:
   pull_request:
     paths-ignore:
       - "**.md"
+    branches:
+      - main
   push:
     paths-ignore:
       - "**.md"
+    branches:
+      - main
 
 jobs:
   build:
-    strategy:
-      matrix:
-        node: [ '20' ]
-    name: CI 🔨🧪🧹
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version: ${{ matrix.node }}
           cache: npm
       - run: npm ci
       - run: npm run build