BUG #34621 added nanosecond support to class Period
Closes #34621
Closes #17053
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`

The class Period do not support nanosecond. I've made a quick and dirty code to support nanoseconds. I have struggled to find an alternative to dateutil.parser, but I didn't found an alternative.

The PR may be a performance issue as I've add a Timestamp constructor to the dateutil.parser. There is for sure a better solution. Please let me know !