Fix/Dokan vendor contact form admin settings

[tanjiralmamun]

In recent updates, Dokan has changed the admin setting screen UI. Due to these changes, the Vendor Contact Form settings have some issues.

This PR has fixed them.

Screenshots: Issues:

• https://snipboard.io/wGUuez.jpg
• https://snipboard.io/9law35.jpg Fixes:
• https://snipboard.io/93Y4Be.jpg
• https://snipboard.io/mkzoLi.jpg