Add Parameter to Customize Number of Recent PRs in post_comments.py

[Anushka-Pote]

Currently, the post_comment function in post_comments.py retrieves the last 10 pull requests for a contributor by default. To enhance flexibility, we need to add a customizable parameter to specify the number of recent PRs retrieved for comment generation. This feature will allow users to specify how many recent PRs to include in the stats, making the function more versatile.

[github-actions]

Welcome @Anushka-Pote! 🎉 Thank you for your first contribution to this project. We're excited to have you on board!