update generate_certificate_exceptions to DRF

[awais786]

verify via instructor postman

It has two options new or all which you can append at the end of url. You can try both urls in postman.

1. Try this URL in postman with post ( new )

2. Try this URL in postman with post ( all)

{
    "success": true,
    "message": "Certificate generation started for students on the allowlist."
}

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verify via instructor dashboard

1. Go to this page
2. choose one option from radio button and press the button.

expected results
It will show the msg below