docs: update cookbook example for SalesGPT - include Stripe Payment L…

…ink Generation (#19622)

Thank you for contributing to LangChain!

- [ ] **cookbook** - update example for SalesGPT - include Stripe
Payment Link Generation

- **Description:** We updated the Jupyter notebook example with the
ability of the AI Agent to negotiate with customers and then close the
deal by generating a custom Stripe payment link.
    - **Issue:** N/A
    - **Dependencies:** N/a
    - **Twitter handle:** @FilipMichalsky @0xtotaylor


If no one reviews your PR within a few days, please @-mention one of
baskaryan, efriis, eyurtsev, hwchase17.

---------

Co-authored-by: Filip Michalsky <[email protected]>
Co-authored-by: Bagatur <[email protected]>