Add New Github Code scanning Alert fields

[ganeshkumarsv]

This PR adds new fields to the Github Code scanning Alert struct to keep the client library updated with the new Github API response.
Github API: https://docs.github.com/en/rest/reference/code-scanning#list-code-scanning-alerts-for-a-repository

[gmlewis]

Whups, I see now that it is a draft... sorry for the early code review. Ah, well... hopefully some of the comments are useful to you.

Also, I'm confused by the description of this PR...
I would have named it something like Add missing Alert fields. Maybe you can clarify what is deprecated.

Oh, and finally, please remember to run gofmt on your edited files. Thanks.

[codecov]

Codecov Report

Merging #2013 (f5839b3) into master (4cbd718) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #2013   +/-   ##
=======================================
  Coverage   97.86%   97.86%           
=======================================
  Files         107      107           
  Lines        6897     6897           
=======================================
  Hits         6750     6750           
  Misses         81       81           
  Partials       66       66           

Impacted Files	Coverage Δ
github/code-scanning.go	100.00% <ø> (ø)

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[ganeshkumarsv]

@gmlewis Yes, the PR is in draft right now. Thanks a lot anyways for your review comments. I have changed the desciption of the PR to Add deprecated alert fields as you mentioned. will address your other comments next week.

[gmlewis]

Thank you, @ganeshkumarsv - just a few minor tweaks, please.

[ganeshkumarsv]

@gmlewis Thanks a lot for the round 2 review comments. I guess I've addressed them. Please let me know if there is anything left to change. :)

[gmlewis]

Thank you, @ganeshkumarsv !
LGTM.
Merging.