Fix sdk license issue with API 28+ system images on Linux.

.github/workflows/workflow.yml

@@ -14,12 +14,14 @@ jobs:
     strategy:
       matrix:
         os: [macos-latest, ubuntu-latest]
-        api-level: [16, 23, 29]
+        api-level: [16, 23, 28, 29]
         exclude:
           - os: ubuntu-latest
             api-level: 23
           - os: ubuntu-latest
             api-level: 29
+          - os: macos-latest
+            api-level: 28
     steps:
     - name: checkout
       uses: actions/checkout@v2