autopep8 generates invalid Python 3.9 multi-line f-string formatting

[martinhoyer]

• original (line-length too long)

            if not node:
                raise tmt.utils.DiscoverError(
                    f"Failed to find plan '{plan_id.name}' at 'url: {plan_id.url}', 'ref: {plan_id.ref}'.")

• autopep8 (Python 3.9 does not support newlines in non-triple-quoted f-strings)

            if not node:
                raise tmt.utils.DiscoverError(
                    f"Failed to find plan '{
                        plan_id.name}' at 'url: {
                        plan_id.url}', 'ref: {
                        plan_id.ref}'.")

• ruff format formats it correctly

        if not node:
            raise tmt.utils.DiscoverError(
                f"Failed to find plan '{plan_id.name}' "
                f"at 'url: {plan_id.url}, 'ref: {plan_id.ref}'."
            )

Ruff-format PR: #2844