fix: Fixed org teams data lookup parent id

[stevehipwell]

Resolves #2491

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Before the change?

• The github_organization_teams data source parent attribute did not provide a usable team ID

After the change?

• The github_organization_teams data source now has a valid parent_team_id attribute
• The github_organization_teams data source now has a parent_team_slug attribute
• The github_organization_teams data source now follows the general idiom for parent team reference

Pull request checklist

• Tests for the changes have been added (for bug fixes / features)
• Docs have been reviewed and added / updated if needed (for bug fixes / features)

Does this introduce a breaking change?

Please see our docs on breaking changes to help!

• Yes
• No

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