Gravity Forms 2.9.1.2

- Updated the database upgrade and System Status page to check for and fix auto increment issues which can cause "duplicate entry 0" errors.
- Fixed an accessibility issue where the notice in the uninstall page doesn't have an alert role.
- Fixed several PHP 8.1 deprecation notices. Note: There are still a number of notices from WordPress 6.0.
- API: Added gform/merge_tag/initialize event to allow merge tag drop downs to be manually initialized after page load.
- API: Updated the REST API v2 [forms/[FORM_ID]/submissions](https://docs.gravityforms.com/submitting-forms-with-rest-api-v2/) endpoint to support the `?_validate_only=1` query argument.

- API: Added [GFAPI::validate_form()](https://docs.gravityforms.com/validating-forms-with-the-gfapi/) to validate form field values without triggering other submission events such as saving the entry, sending notifications, add-on feeds, or confirmations.
- API: Added the [forms/[FORM_ID]/submissions/validation](https://docs.gravityforms.com/validating-forms-with-rest-api-v2/) endpoint to REST API v2.
- API: Updated the gform_field_validation and gform_validation filters to include a new `$context` parameter indicating how the current request was triggered: form-submit, api-submit, or api-validate.
- AF: Updated `GFPaymentAddOn::maybe_validate()` to include `$context` as the second parameter.

- Fixed bug that sometimes results in a fatal error when the license key is empty.