Create main.yml

.github/workflows/main.yml

+name: Build and Push Docker Image
+on:
+  push:
+    branches:
+      - master
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+      - name: Install dependencies & build Nest app
+        run: |
+          npm install
+          npm run build
+      - name: Login to Docker Hub
+        uses: docker/login-action@v1
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v2
+        with:
+          context: .
+          push: true
+          tags: jadenxiong/chat-query:latest