Bump ujson from 4.0.2 to 5.1.0

Bumps [ujson](https://github.com/ultrajson/ultrajson) from 4.0.2 to 5.1.0.
- [Release notes](https://github.com/ultrajson/ultrajson/releases)
- [Commits](https://github.com/ultrajson/ultrajson/compare/4.0.2...5.1.0)

---
updated-dependencies:
- dependency-name: ujson
  dependency-type: direct:production
...

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

requirements.txt

@@ -47,7 +47,7 @@ six==1.16.0
 snowballstemmer==2.0.0
 SQLAlchemy==1.4.15
 toml==0.10.2
-ujson==4.0.2
+ujson==5.1.0
 urllib3==1.26.5
 virtualenv==20.4.6
 waitress==1.4.4