Bump python-rapidjson from 1.5 to 1.6 (#320)

Bumps [python-rapidjson](https://github.com/python-rapidjson/python-rapidjson) from 1.5 to 1.6.
- [Release notes](https://github.com/python-rapidjson/python-rapidjson/releases)
- [Changelog](https://github.com/python-rapidjson/python-rapidjson/blob/master/CHANGES.rst)
- [Commits](python-rapidjson/python-rapidjson@v1.5...v1.6)

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

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements.txt

@@ -26,7 +26,7 @@ pyramid-multiauth==1.0.1
 pyramid-tm==2.4
 pyrsistent==0.18.1
 python-dateutil==2.8.2
-python-rapidjson==1.5
+python-rapidjson==1.6
 repoze.sendmail==4.4.1
 requests==2.27.1
 six==1.16.0