[FEAT]: Support for pull_request merge

[bhoslepu]

Describe the need

Resource repository_pull_request is creating pull request and keep in open state.

• In documentation it says this resource create and manage PullRequests for repositories but there is no argument to merge the Pull Request.

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• Under Attributes sections it outputs state of Pull Request. When Pull Request is manually merged on GitHub Portal it shows closed instead of merged. Little bit confused on state.
  state - the current Pull Request state - can be "open", "closed" or "merged".

SDK Version

No response

API Version

No response

Relevant log output

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[github-actions]

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