feat: add created_at, modified_at in ticket_holder

[codedsun]

Fixes #6655

Short description of what this resolves:

added created_at, modified_at in ticket_holder

Checklist

• I have read the Contribution & Best practices Guide and my PR follows them.
• My branch is up-to-date with the Upstream development branch.
• The unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

• All the functions created/modified in this PR contain relevant docstrings.

[codecov]

Codecov Report

Merging #6660 into development will decrease coverage by <.01%.
The diff coverage is 100%.

@@               Coverage Diff               @@
##           development    #6660      +/-   ##
===============================================
- Coverage        65.33%   65.33%   -0.01%     
===============================================
  Files              298      298              
  Lines            15242    15244       +2     
===============================================
+ Hits              9959     9960       +1     
- Misses            5283     5284       +1

Impacted Files	Coverage Δ
app/models/ticket_holder.py	79.1% <100%> (+0.64%)	⬆️
app/models/event.py	78.57% <0%> (-0.36%)	⬇️

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[codedsun]

@iamareebjamal Sir, please check. Thankyou!

[iamareebjamal]

Verified that it is working correctly?

[codedsun]

@iamareebjamal yes, i did

[iamareebjamal]

So, modified_at changes everytime I send a patch request?

[codedsun]

@iamareebjamal Yes, I checkedin and checked out from frontend.

First column created_at, other verified_at

[codedsun]

Thanks a lot!