Bump flower from 0.9.5 to 1.2.0

Bumps [flower](https://github.com/mher/flower) from 0.9.5 to 1.2.0.
- [Release notes](https://github.com/mher/flower/releases)
- [Commits](mher/flower@v0.9.5...v1.2.0)

---
updated-dependencies:
- dependency-name: flower
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements.txt

@@ -3,7 +3,7 @@ coreapi==2.3.3
 dj-database-url==0.5.0
 timeago==1.0.10
 
-flower==0.9.5
+flower==1.2.0
 tornado<6
 sentry-sdk==0.19.5
 celery==4.2.1