Remove verbose "All pinned actions are up to date" message from stderr

[Copilot]

The action SHA validation was printing a verbose message to stderr when all pinned actions were up to date, adding noise to the compilation output.

Changes

• Removed stderr output in ValidateActionSHAsInLockFile() when all actions are current
• Debug logger message remains available via DEBUG=workflow:action_sha_checker

// Before: printed to stderr in verbose mode
if verbose {
    fmt.Fprintln(os.Stderr, console.FormatVerboseMessage("All pinned actions are up to date"))
}

// After: only in debug logger (already present)
actionSHACheckerLog.Print("All actions are up to date")

Users see cleaner output; developers still have debug visibility when needed.

Original prompt

The message below should be removed and only added to the debug logger.

All pinned actions are up to date

Custom agent used: agentic-workflows
GitHub Agentic Workflows (gh-aw) - Create, debug, and upgrade AI-powered workflows with intelligent prompt routing

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