Add initial setup for Dockerized application

- Added GitHub Actions workflow for building Docker images (.github/workflows/docker-image.yml)
- Created Dockerfile for containerizing the application
- Implemented main application logic in app.py
- Added requirements.txt for managing Python dependencies

.github/workflows/docker-image.yml

@@ -0,0 +1,26 @@
+name: Build and Push Docker Image
+
+on:
+  push:
+    branches: [ "main" ]
+
+jobs:
+  build-and-push:
+    runs-on: ubuntu-latest
+    
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v3
+
+      - name: Log in to Docker Hub
+        uses: docker/login-action@v2
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+
+      - name: Build and push
+        uses: docker/build-push-action@v3
+        with:
+          context: .
+          push: true
+          tags: your-dockerhub-username/random-pdf:latest