Automating BULLETIN.md updates

[Boostrix]

Duplicates

• [X] I have searched the existing issues

Summary 💡

Referring to: #4236

Need to:

• number of new commits / changelog
• retrieve number of closed issues / PRs
• ongoing challenges versus beaten challenges
• help wanted: https://github.com/Significant-Gravitas/Auto-GPT/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22

Examples 🌈

No response

Motivation 🔦

No response