WPForms Stripe Addon 3.4.0

### Changed
- Minimum WPForms version supported is 1.7.5.5.

### Fixed
- Some older migrations were running in incorrect order effectively breaking the Stripe integration by switching users to an older Stripe API version.
- Because of the migrat

### IMPORTANT
- Support for WordPress 5.1 has been discontinued. If you are running WordPress 5.1, you MUST upgrade WordPress before installing the new WPForms Stripe. Failure to do that will disable the new WPForms Stripe functionality.

### Added
- Compatibility with WPForms 1.6.8 and the updated Form Builder.

### Changed
- Show settings in the Form Builder only if they are enabled.
- Connect button UI improvements on Settings > Payments admin page.
- Minimum WPForms version supported is 1.7.5.

### Fixed
- Certain strings were not translatable.
- Improved performance on the WPForms Settings pages.
- The "Name on Card" placeholder value is not updated in the Form Builder preview.
- Some fonts were not working properly with the Credit Card field.
- Compatibility with WordPress Multisite installations.

### Added
- New "Switch Accounts" link in the addon settings to change the Stripe account used.
- Filter to apply custom styles to a Credit Card field.
- Email Notifications option to limit to completed payments only.

### Changed
- Full object is now logged instead of just a message in case of a Stripe error.
- Upgrade Stripe PHP SDK to 7.72.0.

### Fixed
- Edge case when a subscription email is still being required despite changing the payment to single by conditional logic.
- Invalid characters in 'font-family' added by external CSS rules may break the Credit Card field.
- Stripe form with active Captcha fails to submit after Stripe 3DSecure validation.