Bump billiard from 3.6.1.0 to 3.6.2.0 in /requirements (#5950)

Bumps [billiard](https://github.com/celery/billiard) from 3.6.1.0 to 3.6.2.0.
- [Release notes](https://github.com/celery/billiard/releases)
- [Changelog](https://github.com/celery/billiard/blob/master/CHANGES.txt)
- [Commits](https://github.com/celery/billiard/compare/3.6.1...3.6.2.0)

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

requirements/common.txt

@@ -88,7 +88,7 @@ asgiref==3.2.3 \
     --hash=sha256:ea448f92fc35a0ef4b1508f53a04c4670255a3f33d22a81c8fc9c872036adbe5
 
 # Required by celery
-billiard==3.6.1.0 --hash=sha256:01afcb4e7c4fd6480940cfbd4d9edc19d7a7509d6ada533984d0d0f49901ec82 --hash=sha256:b8809c74f648dfe69b973c8e660bcec00603758c9db8ba89d7719f88d5f01f26
+billiard==3.6.2.0 --hash=sha256:26fd494dc3251f8ce1f5559744f18aeed427fdaf29a75d7baae26752a5d3816f --hash=sha256:f4e09366653aa3cb3ae8ed16423f9ba1665ff426f087bcdbbed86bf3664fe02c
 pytz==2019.2 \
     --hash=sha256:c894d57500a4cd2d5c71114aaab77dbab5eabd9022308ce5ac9bb93a60a6f0c7 \
     --hash=sha256:26c0b32e437e54a18161324a2fca3c4b9846b74a8dccddd843113109e1116b32