chore(dependencies): Bump yarl from 0.15.0 to 0.16.0 in /backend/uclapi
chore(dependencies): Bump yarl from 0.15.0 to 0.16.0 in /backend/uclapi

Bumps [yarl](https://github.com/aio-libs/yarl) from 0.15.0 to 0.16.0.
- [Release notes](https://github.com/aio-libs/yarl/releases/tag/v0.16.0)
- [Changelog](https://github.com/aio-libs/yarl/blob/master/CHANGES.rst)
- [Commits](https://github.com/aio-libs/yarl/compare/v0.15.0...v0.16.0)
uclapi/uclapi,uclapi/uclapi,uclapi/uclapi,uclapi/uclapi