Add support for `type` parameter to get_issues (#3381)

## 1. Describe the problem the Pull Request attempts to solve

This pull request adds support for the [`type` query
parameter](https://docs.github.com/en/rest/issues/issues?apiVersion=2022-11-28#list-repository-issues).
a feature recently added to the GitHub Issues. Currenty PyGithub's
`get_issues` method does not have a way to filter issues by their type.

## 2. Explain how the you went about solving the problem

I have updated the `get_issues` method in `github/Repository.py` to
accept a new optional `type` parameter. When this parameter is provided,
it is included in the URL parameter for API request.

## 3. Provide a test that exemplifies the expected behaviour

I have added two test methods, `testGetIssuesWithTypeArgument` and
`testGetIssuesWithTypeWildcard`.

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*As my native language is not English, I apologize for any errors in my
writing.*

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Co-authored-by: Enrico Minack <github@enrico.minack.dev>