Maintenance of python project template

[rwood-97]

https://github.com/alan-turing-institute/python-project-template

TODO:

• New release
• ty in pre-commit
• cd as optional (add codecov and pypi options python-project-template#48), update this PR to delete the cd file by default if no pypi selected.
• merge PRs
• make ty optional

@andrewphilipsmith @alexeatscake

[rwood-97]

Thanks @phinate for all your work on this up to now :)