Bump locust from 2.15.1 to 2.31.2

Bumps [locust](https://github.com/locustio/locust) from 2.15.1 to 2.31.2.
- [Release notes](https://github.com/locustio/locust/releases)
- [Changelog](https://github.com/locustio/locust/blob/master/CHANGELOG.md)
- [Commits](locustio/locust@2.15.1...2.31.2)

---
updated-dependencies:
- dependency-name: locust
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

requirements/test.txt

@@ -1,5 +1,5 @@
 # Only needed to run tests.
 coveralls==3.3.1
 coverage==6.3.2
-locust==2.15.1
+locust==2.31.2
 tblib==3.0.0