chore(deps): upgrade to Python 3.12 and prepare for 0.6.0 release

- Update Docker base image to Python 3.12-slim-bookworm
- Bump version from 0.6.0rc1 to 0.6.0
- Update documentation to reflect release version changes
- Fix license specification in pyproject.toml and setup.py
- Clean up code formatting in demo_docker_api.py

BREAKING CHANGE: Base Python version upgraded from 3.10 to 3.12

deploy/docker/README.md

@@ -62,7 +62,7 @@ Our latest release candidate is `0.6.0rc1-r1`. Images are built with multi-arch
 
 ```bash
 # Pull the release candidate (recommended for latest features)
-docker pull unclecode/crawl4ai:0.6.0rc1-r1
+docker pull unclecode/crawl4ai:0.6.0-rN # Use your favorite revision number
 
 # Or pull the latest stable version
 docker pull unclecode/crawl4ai:latest
@@ -99,7 +99,7 @@ EOL
       -p 11235:11235 \
       --name crawl4ai \
       --shm-size=1g \
-      unclecode/crawl4ai:0.6.0rc1-r1
+      unclecode/crawl4ai:0.6.0-rN # Use your favorite revision number
     ```
 
 *   **With LLM support:**
@@ -110,7 +110,7 @@ EOL
       --name crawl4ai \
       --env-file .llm.env \
       --shm-size=1g \
-      unclecode/crawl4ai:0.6.0rc1-r1
+      unclecode/crawl4ai:0.6.0-rN # Use your favorite revision number
     ```
 
 > The server will be available at `http://localhost:11235`. Visit `/playground` to access the interactive testing interface.
@@ -160,7 +160,7 @@ The `docker-compose.yml` file in the project root provides a simplified approach
     ```bash
     # Pulls and runs the release candidate from Docker Hub
     # Automatically selects the correct architecture
-    IMAGE=unclecode/crawl4ai:0.6.0rc1-r1 docker compose up -d
+    IMAGE=unclecode/crawl4ai:0.6.0-rN # Use your favorite revision number docker compose up -d
     ```
 
 *   **Build and Run Locally:**