Skip pytz expectation to fix broken tests [gemnasium-python only]

What does this MR do?

Set pytz to :SKIP: to fix the following test failures:

• python-pipenv-require-system-python-FREEZE
• python-pipenv-offline-FREEZE
• python-pipenv-master
• python-setuptools-offline-FREEZE
• python-setuptools-main

What are the relevant issue numbers?

N/A

Does this MR meet the acceptance criteria?

• [-] Changelog entry added
• Documentation created/updated for GitLab EE, if necessary
• Documentation created/updated for this project, if necessary
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Job definition updated, if necessary
  • Auto-DevOps template
  • Job definition example
  • CI Templates
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer