Add datree-validation.yml

[datreeio]

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[what-the-diff]

PR Summary

• Triggered on pull_request events
  The workflow activates when a pull_request event occurs.
• Checks for changed YAML files
  The repository is checked for any modifications in YAML files.
• Installs Datree's CLI tool
  If any changes are detected, Datree's CLI tool is installed using a curl command from the provided URL.
• Runs action-datree GitHub Action
  Upon detecting changes, the action-datree GitHub Action is executed to validate configuration files according to the organization's policies.