feat: Add support for Issue Types API

[atilsensalduz]

This pull request introduces support for the Issue Types API to the go-github library, enabling users to manage issue types within their organizations. The following functions have been added:

• ListIssueTypes: Retrieves all issue types for a specified organization.
• CreateIssueType: Allows the creation of a new issue type within an organization.
• UpdateIssueType: Enables updating the attributes of an existing issue type.
• DeleteIssueType: Facilitates the deletion of an issue type from an organization.

Each function is accompanied by comprehensive tests to ensure functionality and reliability.

API References: https://docs.github.com/en/rest/orgs/issue-types

Fixes: #3523

Please let me know if any additional changes or improvements are needed!

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.30%. Comparing base (a03e88c) to head (8a6fa7d).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3525      +/-   ##
==========================================
+ Coverage   91.27%   91.30%   +0.02%     
==========================================
  Files         183      184       +1     
  Lines       16099    16143      +44     
==========================================
+ Hits        14695    14739      +44     
  Misses       1230     1230              
  Partials      174      174              

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[gmlewis]

It looks like the openapi stuff is a problem afterall.
I'm thinking I should make a separate PR to update openapi, then you can merge it from master and your PR can then be focused on just your changes. I'll do that today.

[gmlewis]

This looks great, @atilsensalduz!
Just one minor tweak, please.

[atilsensalduz]

Tests are passed in my local. @gmlewis could you please rerun the test?

wdyt to add small delay in here?
https://github.com/google/go-github/blob/master/github/github_test.go#L67

	// Add a slight delay before closing the server to prevent race conditions
	t.Cleanup(func() {
		time.Sleep(100 * time.Millisecond) // Ensures all requests complete
		server.Close()
	})

before:
script/test.sh 8.05s user 10.24s system 145% cpu 12.584 total

after:
script/test.sh 10.47s user 12.00s system 83% cpu 26.990 total

[gmlewis]

wdyt to add small delay in here?

What I would really like to understand is WHY we have any race conditions at all.
There should be a way to close down the server reliably without any use of sleep, and I would love to get to the bottom of it. Can you please file an issue, @atilsensalduz, and/or investigate if you feel like it?

[gmlewis]

Thank you, @atilsensalduz and @Wisma-55!
LGTM.
Merging.