Get API working with Poetry 1.2

[Reillyhewitson]

Description:
Poetry 1.2 can cause issues with our dependencies if it updates the lockfile.

Acceptance criteria:

• Github actions works with poetry 1.2

[VKTB]

Poetry 1.2 requires Python 3.7+ to run.

[MRichards99]

More info at https://python-poetry.org/blog/announcing-poetry-1.2.0/#dropping-support-for-python-27-35-and-36-as-runtimes

[MRichards99]

This cannot be tackled until #428 is resolved - Poetry 1.2 drops runtime support for 3.6, don't really want to be developing against 3.7+ when we still have to use 3.6 in production.

[MRichards99]

The latest version of Poetry should be targeted when this issue is tackled, it is currently at 1.8.3. See https://python-poetry.org/history/ for the changelog. This issue would be a good chance for all the other 'infrastructure' dependencies to be upgraded - nox, black, safety, flake8 etc.