Bump lxml from 4.5.1 to 4.5.2 in /requirements (#14906)
Bump lxml from 4.5.1 to 4.5.2 in /requirements (#14906)

Bumps [lxml](https://github.com/lxml/lxml) from 4.5.1 to 4.5.2.
- [Release notes](https://github.com/lxml/lxml/releases)
- [Changelog](https://github.com/lxml/lxml/blob/master/CHANGES.txt)
- [Commits](https://github.com/lxml/lxml/compare/lxml-4.5.1...lxml-4.5.2)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>

Co-authored-by: dependabot[bot] <1c358da00a777d4e9898c1280ab801e2df165188@users.noreply.github.com>
mozilla/olympia,wagnerand/addons-server,mozilla/olympia,diox/olympia,wagnerand/addons-server,wagnerand/addons-server,mozilla/addons-server,mozilla/olympia,mozilla/olympia,eviljeff/olympia,mozilla/addons-server,bqbn/addons-server,diox/olympia,bqbn/addons-server,mozilla/addons-server,eviljeff/olympia,eviljeff/olympia,diox/olympia,eviljeff/olympia,wagnerand/addons-server,bqbn/addons-server,diox/olympia,bqbn/addons-server,mozilla/addons-server