Allow most recent pytz version and update dependencies

[micahellison]

See #783. This PR allows the most recent version of pytz and updates the lockfile to the most recent allowable versions from pyproject.toml.

The only impact of the pytz update is on DayOneJournal.py.

Checklist

• The code change is tested and works locally.
• Tests pass. Your PR cannot be merged unless tests pass. --
  poetry run behave
• The code passes linting via
  black (consistent code styling). --
  poetry run black --check . --verbose --diff
• The code passes linting via pyflakes
  (logically errors and unused imports). -- poetry run pyflakes jrnl features
• There is no commented out code in this PR.
• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open
  Pull Requests for the same update/change?
• Have you added an explanation of what your changes do and why you'd like
  us to include them?
• [n/a] Have you written new tests for your core changes, as applicable?

[wren]

🎉