Allow Stripe >= 10.11, < 13.0

[henrikbjorn]

Pull Request

Summary:

Allow installing Stripe 12 and loosen the constraint since there hasn't been any significant changes between 10.11 and 12.

Related Issue:

Description:

Testing:

Screenshots (if applicable):

Checklist:

• [x] Code follows the project's coding standards
• [x] Tests have been added or updated to cover the changes
• [x] Documentation has been updated (if applicable)
• [ ] All existing tests pass
• [x] Conforms to the contributing guidelines

Additional Notes:

[excid3]

Each Stripe major version change updates their API version so we want to be explicit with it.

[henrikbjorn]

@excid3 Any reason for closing it, instead of letting me update the version constraint to ~> 12.0 ?