⬆ Update fastapi requirement

Updates the requirements on [fastapi](https://github.com/fastapi/fastapi) to permit the latest version.
- [Release notes](https://github.com/fastapi/fastapi/releases)
- [Commits](fastapi/fastapi@0.103.2...0.128.0)

---
updated-dependencies:
- dependency-name: fastapi
  dependency-version: 0.128.0
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements-tests.txt

@@ -5,7 +5,7 @@ coverage[toml] >=6.2,<8.0
 mypy ==1.19.1
 ruff ==0.14.10
 # For FastAPI tests
-fastapi >=0.103.2,<0.126.0
+fastapi >=0.103.2,<0.129.0
 httpx ==0.28.1
 dirty-equals ==0.11
 jinja2 ==3.1.6