add docker publish action

.github/workflows/docker-publish.yml

@@ -0,0 +1,31 @@
+name: Build and Push Docker Image
+
+on:
+  push:
+    branches:
+      - main  # Change this to the branch you want to trigger builds on
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v2
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_TOKEN }}
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v2
+
+      - name: Build and push Docker image
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          push: true
+          tags: poeli/wastewater_qpcr_app:latest
+          file: Dockerfile  # Update this if your Dockerfile has a different name or location