Form validation

### Description of the issue
The seller signup page didn't validation

### Expected result
If the user fills invalid information It should not accept the information and show the alert fil the required information

### Actual result
If user fills invalid information The form also accept the invalid information

### Steps to reproduce
1. Go to home page click the seller button
2. Fill the form in invalid information
3. The form accept the invalid information and redirect to the login page

```
Path: /index.html#chinise
Browser: Chrome 113.0.0.0 on Windows 10
Viewport: 1504 x 860 @1.5x
Language: en-GB
Cookies: Enabled
```

[Open in BrowserStack](https://www.browserstack.com/user/try-live?url=https%3A%2F%2Fdeploy-preview-6--https-fresh-food.netlify.app%2Findex.html%23chinise&os=Windows&os_version=10&browser=Chrome&browser_version=113.0&resolution=1504x860&speed=1&start=true&ref=netlify-source)

Submitted from [Netlify Deploy Preview #6](https://deploy-preview-6--https-fresh-food.netlify.app/index.html#chinise)

Start in /index.html at the seller signup form linked by the #chinise path, and reproduce the behavior in Chrome using invalid information. Review the form's current validation flow. Done means invalid submissions show an alert, are rejected, and do not redirect to the login page.

Written by the indexing model from the issue text.