* Fixed balanced_parentheses.py

* fixed pre-commit

* eliminate is_paired

* remove unused line

* updating DIRECTORY.md

* Update data_structures/stacks/balanced_parentheses.py
Co-authored-by: NChristian Clauss <cclauss@me.com>

* Add more test cases

* Update data_structures/stacks/balanced_parentheses.py
Co-authored-by: NChristian Clauss <cclauss@me.com>
Co-authored-by: Ngithub-actions <${GITHUB_ACTOR}@users.noreply.github.com>
Co-authored-by: NChristian Clauss <cclauss@me.com>