fix(ci): install ninja

.github/workflows/ci.yml

@@ -25,7 +25,7 @@ jobs:
         run: deno lint
 
   test:
-    runs-on: macos-latest
+    runs-on: ubuntu-latest
     steps:
       - name: Setup repo
         uses: actions/checkout@v2
@@ -37,6 +37,9 @@ jobs:
         with:
           deno-version: "v2.x"
 
+      - name: Install Ninja
+        run: sudo apt-get install ninja-build
+
       - name: Build Yoga
         run: deno task build-yoga