add create invitation with payments to lightspark sdk

[matthappens]

Add create_uma_invitation_with_payment to SDK

This PR adds a new method create_uma_invitation_with_payment to the Lightspark client, allowing users to create UMA invitations that include payment details. The implementation includes:

• A new GraphQL mutation in create_uma_invitation.py
• The corresponding client method in lightspark_client.py with proper documentation
• Support for payment amount, currency details, and expiration time

[matthappens]

• add cancel uma invitation mutation to py sdk #64
• add create invitation with payments to lightspark sdk #63 👈 (View in Graphite)
• main

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