Update fastapi due to vulnerability.

[busykoala]

Purpose

To mitigate CVE-2024-24762,
we need to update FastAPI. This update necessitates discontinuing support for
Python 3.7.

Approach

To ensure our FastAPI dependency is secure, we've pinned it to a version that
addresses the vulnerability. However, this version also discontinues support
for Python 3.7, requiring us to do the same.

Checklist for PRs

• There is a Changelog (/CHANGELOG.md)
• Version was adapted if necessary (/pyproject.toml)
• I tested the feature if necessary (unittests, manual testing)
• If libraries aren't used for all package usages they are extras
• I documented the changes