Bump eventlet from 0.30.2 to 0.31.0 in /st2common

Bumps [eventlet](https://github.com/eventlet/eventlet) from 0.30.2 to 0.31.0.
- [Release notes](https://github.com/eventlet/eventlet/releases)
- [Changelog](https://github.com/eventlet/eventlet/blob/master/NEWS)
- [Commits](eventlet/eventlet@v0.30.2...v0.31.0)

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

Author: dependabot[bot]

st2common/requirements.txt

@@ -10,7 +10,7 @@ apscheduler==3.7.0
 chardet<3.1.0
 cryptography==3.4.7
 dnspython>=1.16.0,<2.0.0
-eventlet==0.30.2
+eventlet==0.31.0
 flex==6.14.1
 git+https://github.com/StackStorm/[email protected]#egg=orquesta
 git+https://github.com/StackStorm/st2-rbac-backend.git@master#egg=st2-rbac-backend