Create docker-image.yml

Needs Docker Hub credentials to the GitHub repository secrets (DOCKERHUB_USERNAME and DOCKERHUB_TOKEN). Also needs USER tag to match Docker Hub username.

.github/workflows/docker-image.yml

@@ -0,0 +1,27 @@
+name: Docker Image CI
+
+on:
+  push:
+    branches: [ "master" ]
+  pull_request:
+    branches: [ "master" ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - name: Set up Docker Buildx
+      uses: docker/build-push-action@v4
+    - name: Login to DockerHub
+      uses: docker/login-action@v2
+      with:
+        username: ${{ secrets.DOCKERHUB_USERNAME }}
+        password: ${{ secrets.DOCKERHUB_TOKEN }}
+    - name: Build and push
+      uses: docker/build-push-action@v4
+      with:
+        context: .
+        file: ./Dockerfile
+        push: true
+        tags: USER/sygil-webui:latest