chore(ci): removed useless matrix

.github/workflows/ci.yml

@@ -4,12 +4,7 @@ on: [pull_request, push]
 
 jobs:
   ci:
-    runs-on: ${{ matrix.os }}
-
-    strategy:
-      matrix:
-        os: [ubuntu-latest]
-        node: [14]
+    runs-on: ubuntu-latest
 
     steps:
       - name: Checkout
@@ -18,7 +13,7 @@ jobs:
       - name: Setup node env
         uses: actions/setup-node@v2.1.2
         with:
-          node-version: ${{ matrix.node }}
+          node-version: 14
 
       - name: Cache node_modules
         uses: actions/cache@v2