build(deps): Bump libmozdata from 0.1.59 to 0.1.60 in /bot (#259)

Bumps [libmozdata](https://github.com/mozilla/libmozdata) from 0.1.59 to 0.1.60.
- [Release notes](https://github.com/mozilla/libmozdata/releases)
- [Commits](https://github.com/mozilla/libmozdata/commits)

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

Author: dependabot-preview[bot]

bot/requirements.txt

@@ -1,6 +1,6 @@
 -e ../tools #egg=code-coverage-tools
 google-cloud-storage==1.20.0
-libmozdata==0.1.59
+libmozdata==0.1.60
 pytoml==0.1.21
 pytz==2019.3
 zstandard==0.12.0