Change docker build action to push to GHCR

.github/workflows/docker-image.yml

@@ -1,11 +1,26 @@
 name: Docker Image CI
+
 on:
   push:
     branches: [ "main" ]
+
 jobs:
-  build:
+  build-and-push:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4
-    - name: Build the Docker image
-      run: docker build . --file Dockerfile --tag portfolio:$(date +%s)
+
+    - name: Log in to GitHub Container Registry
+      uses: docker/login-action@v3
+      with:
+        registry: ghcr.io
+        username: ${{ github.actor }}
+        password: ${{ secrets.GITHUB_TOKEN }}
+
+    - name: Build and push Docker image
+      uses: docker/build-push-action@v5
+      with:
+        context: .
+        push: true
+        tags: |
+          ghcr.io/${{ github.repository_owner }}/portfolio:latest