enable poetry install by adding pyproject.toml and supporting shell script

[hobson]

• fix issue #40
• does not fix any tests and has not been fully tested (only runserver on Django >4.0, Python >3.8). The newly added runtests.sh fails on main with or without this pyproject.toml
• added poetry install as 2nd option in setup.md
• runtests.sh is missing and the one I created is broken (see Issue #41)