Drop Python 3.7 Support

[VKTB]

Description:
The support for Python 3.7 will end at the end of June 2023. Similarly to #428, supporting this version of Python will shortly become an issue.

Acceptance criteria:

• Make the project work with Python 3.8 as the minimum version and update dependencies (including vulnerable ones where possible) accordingly
• Update any code that was added as a workaround for Python 3.7 to work with Python 3,8
• All CI checks pass
• Make a major release in terms of versioning

[MRichards99]

Superseded by #490