As a developer I want to use pytest

Pytest test are easier to maintain especially with database related fixtures.

DOD:
- all current test are rewritten to PyTest
- fixtures and conftest are available to create a DB with test (2 projects, 4 sprints, 2 wishes, 4 epics, 8 userstories with different states and assigned sprints)

Start by locating the current test suite and Django test configuration, then identify where pytest fixtures and conftest.py would fit. Review the existing database-related tests and compare them with the stated data set. Done means all current tests use pytest and reusable fixtures can create the two projects, four sprints, two wishes, four epics, and eight user stories with varied states and sprint assignments.

索引モデルが issue の本文から書いたものです。