Contract updated

[RijuChakraborty]

Changes I've made

1. Solidity version updated to ^0.8.0
2. This changes have helped to reduce gas costs by 20k -
   i. "uint public videoCount = 0" has been removed as uint datatype gets initialized with 0 by default in solidity.
   ii. name is declared as a constant value
   iii. empty constructor is removed
   iv. require statements have been replaced with IF => then revert an error structure

Type of change

• Enhancements done to existing code
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, local variables)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

This changes have been tested by deploying contract instances in Remix ide.
Code produces 0 errors and 0 warnings.
Code is working as per required.

Checklist:

• My code follows the "contribution guidelines" of this project.
• I have performed a self-review of my own code.
• I have commented my code, particularly wherever it was hard to understand.
• My changes generate no new warnings.
• Any dependent changes have been merged and published in downstream modules.