captcha Feature added

[badaya12]

Description

I have added the feature of Recaptcha that does robot verification .I have used v3 version that works invisibly which eliminates the issues arises due to disability and linguistic barrier.

Related Issues

Feature Request: Add Robot Verification #1102

Steps to Test

First you have to acquire recaptcha site_key and Secret Key from recaptcha which provides free 100000 verification for free.
then

1. In the backend first replaces secret in .env
2. In the frontend replace site key in .env
3. in index.html replace YOUR_SITE_KEY with key itself.

Checklist

• [NO ] I have tested these changes
• [ NO] I have updated the relevant documentation
• [YES ] I have commented my code, particularly in hard-to-understand areas
• [YES ] I have made corresponding changes to the codebase
• [ YES] My changes generate no new warnings or errors
• [ YES] The title of my pull request is clear and descriptive