Fix shell quoting in verify-gomod failure messaging

[Copilot]

The verify-gomod GitHub Actions job was failing with a misleading shell error from .github/scripts/check-gomod.sh. Instead of only reporting an out-of-date module file, the script executed its remediation hint because the message used backticks.

• Root cause

  • Failure-path messages in check-gomod.sh used backticks:
    • `cd actions && go mod tidy`
    • `cd interoperability && go mod tidy`
  • In Bash, backticks trigger command substitution, so the hint was executed while building the error output.

• Change

  • Replace backticks with quoted literals in the remediation messages for:
    • actions
    • interoperability
  • Keep the script behavior unchanged outside the failure messaging path.

• Effect

  • verify-gomod now reports the actual module drift cleanly, without injecting unrelated cd errors into the logs.
  • The failure output is now actionable and points directly to the required tidy command.

# before
echo "actions Go mod isn't up to date. Please run `cd actions && go mod tidy`"

# after
echo "actions Go mod isn't up to date. Please run 'cd actions && go mod tidy'"