add GHUser#suspendedAt

[styner9]

Description

Add GHUser#suspendedAt to check whether user is suspended or not.
Fix #1796.

Before submitting a PR:

• Changes must not break binary backwards compatibility. If you are unclear on how to make the change you think is needed while maintaining backward compatibility, CONTRIBUTING.md for details.
• Add JavaDocs and other comments explaining the behavior.
• When adding or updating methods that fetch entities, add @link JavaDoc entries to the relevant documentation on https://docs.github.com/en/rest .
• Add tests that cover any added or changed code. This generally requires capturing snapshot test data. See CONTRIBUTING.md for details.
• Run mvn -D enable-ci clean install site locally. If this command doesn't succeed, your change will not pass CI.
• Push your changes to a branch other than main. You will create your PR from that branch.

When creating a PR:

• Fill in the "Description" above with clear summary of the changes. This includes:
  • If this PR fixes one or more issues, include "Fixes #" lines for each issue.
  • Provide links to relevant documentation on https://docs.github.com/en/rest where possible. If not including links, explain why not.
• All lines of new code should be covered by tests as reported by code coverage. Any lines that are not covered must have PR comments explaining why they cannot be covered. For example, "Reaching this particular exception is hard and is not a particular common scenario."
• Enable "Allow edits from maintainers".

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.32%. Comparing base (af5bde7) to head (7e7e088).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main    #1906   +/-   ##
=========================================
  Coverage     81.32%   81.32%           
- Complexity     2457     2458    +1     
=========================================
  Files           239      239           
  Lines          7463     7464    +1     
  Branches        400      400           
=========================================
+ Hits           6069     6070    +1     
  Misses         1147     1147           
  Partials        247      247           

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