build(deps): Bump tenacity from 6.0.0 to 6.1.0 in /bot (#435)

Bumps [tenacity](https://github.com/jd/tenacity) from 6.0.0 to 6.1.0.
- [Release notes](https://github.com/jd/tenacity/releases)
- [Commits](jd/tenacity@6.0.0...6.1.0)

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

Author: dependabot-preview[bot]

bot/requirements.txt

@@ -3,5 +3,5 @@ google-cloud-storage==1.26.0
 libmozdata==0.1.64
 pytoml==0.1.21
 pytz==2019.3
-tenacity==6.0.0
+tenacity==6.1.0
 zstandard==0.13.0