feat(pr/body): add gpt-pr signature in PRs

[alissonperez]

What was done?

Added a feature to include a GPT-PR signature in pull requests to enhance transparency and collaboration among developers. Updated the README to reflect new settings and usage instructions.

How was it done?

• Implemented a new method in the PrData class to append a signature to the PR body if the configuration allows it.
• Updated the configuration management to include a new setting for enabling/disabling the signature feature.
• Modified the README to include instructions on how to set the maximum input tokens and how to enable/disable the GPT-PR signature.

How was it tested?

• Verified that the signature is appended to the PR body when the configuration is set to true.
• Ensured that the README updates are accurate and reflect the new features correctly.
• Conducted unit tests to confirm that the configuration settings are being read and applied correctly.

---

Generated by GPT-PR