Gravity Perks - Preview Submission 1.3.24

Fixed conflict where Preview Submission was preventing merge tag drop downs for other plugins/perks such as GP Unique ID from showing fields on the current page.
Added "Update URI" to plugin header to improve security.

- Fixed issue where File Upload fields in Nested Forms would not show their values in merge tags parsed by GP Preview Submission.

Fixed issue where Section fields with only File Upload fields would not show when previewing the {all_fields} merge tag.