Create Github actions file for automating docker image build

.github/workflows/docker.yml

@@ -0,0 +1,35 @@
+name: Build & Push Multi-Arch Docker Image
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  docker-build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v4
+
+      - name: Set up QEMU for multi-arch builds
+        uses: docker/setup-qemu-action@v3
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+      - name: Build and push multi-arch image
+        uses: docker/build-push-action@v5
+        with:
+          context: .
+          file: ./Dockerfile
+          platforms: linux/amd64,linux/arm64
+          push: true
+          tags: bytebard101/cosmoclassifier:latest