Typo preventing bumpversion to work in some case

Version 6.3.3

Found out a typo preventing bumpversion CLI to work correclty in one case (see here)

Current version: bumpversion ${TRACE+--verbose} --commit ${PYTHON_RELEASE_COMMIT_MESSAGE+--message "$PYTHON_RELEASE_COMMIT_MESSAGE"} "$PYTHON_RELEASE_COMMIT_MESSAGE" --tag --tag-name "{new_version}" "$py_release_part"

Fixed version: bumpversion ${TRACE+--verbose} --commit ${PYTHON_RELEASE_COMMIT_MESSAGE+--message "$PYTHON_RELEASE_COMMIT_MESSAGE"} --tag --tag-name "{new_version}" "$py_release_part"