ci: convert from Travis to Github Actions

Signed-off-by: Agnes Lin <agneslin.lin@ibm.com>

.github/workflows/continuous-integration.yaml

@@ -0,0 +1,27 @@
+name: Continuous Integration
+
+on:
+  push:
+    branches:
+    - master
+  pull_request:
+    branches:
+    - master
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [8, 10, 12]
+    steps:
+    - name: Git checkout
+      uses: actions/checkout@v2
+
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v1
+      with:
+        node-version: ${{ matrix.node-version }}
+
+    - run: npm install
+    - run: npm test

.travis.yml

@@ -1,5 +0,0 @@
-language: node_js
-node_js:
-  - "8"
-  - "10"
-  - "12"