Verify grep portability in sync-upstream.yml - no changes needed

[Copilot]

Addresses feedback on grep pattern portability in .github/workflows/sync-upstream.yml:46.

Summary

The grep pattern already uses the explicit -E flag for extended regex:

grep -v -E '(alpha|beta|rc)'

This is POSIX-compliant and portable across all modern systems. Verified the pattern correctly filters pre-release tags (alpha/beta/rc) from version detection.

No code changes required - implementation already follows best practices.

Checklist

• I have read the contribution guide.
• I have not used an AI coding assistant to create this PR.
• I have written all code in this PR myself OR I have marked all code I have not written myself (including modified code, e.g. copied from other places and then modified) with a comment indicating where it came from.
• I (and other contributors to this PR) have not looked at the Terraform source code while implementing this PR.

Go checklist

• I have run golangci-lint on my change and receive no errors relevant to my code.
• I have run existing tests to ensure my code doesn't break anything.
• I have added tests for all relevant use cases of my code, and those tests are passing.
• I have only exported functions, variables and structs that should be used from other packages.
• I have added meaningful comments to all exported functions, variables, and structs.

Website/documentation checklist

• I have locally started the website as described here and checked my changes.

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[github-actions]

Reminder for the PR assignee: If this is a user-visible change, please update the changelog as part of the PR.