Add github docker building action

Added the Docker workflow with image building and pushing to Docker Hub.

Author: shagohead

.github/workflows/docker-image.yml

@@ -0,0 +1,22 @@
+name: Docker Image CI
+
+on:
+  push:
+    branches: [ "main" ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Login to Docker Hub
+      uses: docker/login-action@v4
+      with:
+        username: ${{ vars.DOCKERHUB_USERNAME }}
+        password: ${{ secrets.DOCKERHUB_TOKEN }}
+    - name: Set up Docker Buildx
+      uses: docker/setup-buildx-action@v4
+    - name: Build and push
+      uses: docker/build-push-action@v7
+      with:
+        push: true
+        tags: ${{ vars.DOCKERHUB_USERNAME }}/bugpack:latest