build(deps): bump libmozevent from 1.1.6 to 1.1.8 in /events (#936)

Bumps [libmozevent](https://github.com/mozilla/libmozdata) from 1.1.6 to 1.1.8.
- [Release notes](https://github.com/mozilla/libmozdata/releases)
- [Commits](https://github.com/mozilla/libmozdata/commits)

---
updated-dependencies:
- dependency-name: libmozevent
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

events/requirements.txt

@@ -4,7 +4,7 @@ aioredis==1.3.1
 json-e==4.4.1
 jsonschema==3.2.0
 libmozdata==0.1.72
-libmozevent==1.1.6
+libmozevent==1.1.8
 python-hglib==2.6.2
 pytoml==0.1.21
 pyyaml==5.4.1