Add Optional private_repo_password Input to Action

[dwertent]

This pull request introduces an optional input to the GitHub Action, private_repo_password. This input allows users to provide a password for accessing a private repository if necessary.

Changes include:

• An update to action.yml to define the new private_repo_password input.
• Modifications to action.ts to retrieve the private_repo_password input and, if provided, write it to the ~/.netrc file.

This change enhances the action's flexibility by allowing it to interact with private repositories, expanding its use cases.

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