chore: add action to publish expo app

.github/workflows/expo.yml

@@ -0,0 +1,44 @@
+name: Expo Publish
+on:
+  push:
+    branches:
+      - master
+
+jobs:
+  publish:
+    name: Install and publish
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v1
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v1
+        with:
+          node-version: 10.x
+
+      - name: Setup Expo
+        uses: expo/expo-github-action@v5
+        with:
+          expo-version: 3.x
+          expo-username: ${{ secrets.EXPO_CLI_USERNAME }}
+          expo-password: ${{ secrets.EXPO_CLI_PASSWORD }}
+          expo-cache: true
+
+      - name: Get yarn cache
+        id: yarn-cache
+        run: echo "::set-output name=dir::$(yarn cache dir)"
+
+      - uses: actions/cache@v1
+        with:
+          path: ${{ steps.yarn-cache.outputs.dir }}
+          key: ${{ runner.os }}-yarn-${{ hashFiles('**/yarn.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-yarn-
+
+      - name: Install dependencies
+        run: yarn
+
+      - name: Publish Expo app
+        working-directory: ./example
+        run: expo publish