chore: Update Terraform required_version for consistency

[Nepomuceno]

Description

This PR updates the Terraform required_version constraint to ensure consistency across all AVM modules. The constraint has been set to >= 1.9, < 2.0 to maintain compatibility and leverage the features available in Terraform versions within this range.

Type of Change

• Non-module change (e.g., CI/CD, documentation, etc.)
• Azure Verified Module updates:
  • Bugfix containing backwards compatible bug fixes
    • Someone has opened a bug report issue, and I have included "Closes #{bug_report_issue_number}" in the PR description.
    • The bug was found by the module author, and no one has opened an issue to report it yet.
  • Feature update backwards compatible feature updates.
  • Breaking changes.
  • Update to documentation

Checklist

• I'm sure there are no other open Pull Requests for the same update/change
• My corresponding pipelines / checks run clean and green without any errors or warnings
• I did run all pre-commit checks

[microsoft-github-policy-service]

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