introduce new cronjob setup feature

[jessebot]

you can now include cron in the lists in ~/.config/onboardme/config.yaml:

# steps refer to a specific function in the list of functions we run
steps:
  # mac specific steps
  Darwin:
    - dot_files
    - cron
  # linux specific steps
  Linux:
    - dot_files
    - cron

This will copy the files:

• ~/.config/cron/root/crontab to /etc/crontab.d/root (or /var/at/tabs/root in macOS)
• ~/.config/cron/user/crontab to /etc/crontab.d/YOUR_USER (or /var/at/tabs/YOUR_USER in macOS)

---

also takes care of some dependency updates:

• Updating distlib (0.3.8 -> 0.3.9)
• Updating filelock (3.15.4 -> 3.16.1)
• Updating platformdirs (4.2.2 -> 4.3.6)
• Updating identify (2.6.0 -> 2.6.1)
• Updating pyyaml (6.0.1 -> 6.0.2)
• Updating virtualenv (20.26.3 -> 20.27.0)
• Updating pre-commit (3.7.1 -> 3.8.0)
• Updating rich (13.7.1 -> 13.9.2)
• Updating xdg-base-dirs (6.0.1 -> 6.0.2)