MFH: r501623 r503238

devel/py-buildbot{-*}: Update to 2.3.0

Changelog:

https://docs.buildbot.net/current/relnotes/index.html#buildbot-2-3-0-2019-05-06

devel/py-buildbot{-*}: Update to 2.3.1

This release fixes a vulnerability in OAuth where user-submitted
authorization token was used for authentication. [1][2]

Changelog:

https://docs.buildbot.net/current/relnotes/index.html#buildbot-2-3-1-2019-05-22

[1] https://github.com/buildbot/buildbot/wiki/OAuth-vulnerability-in-using-submitted-authorization-token-for-authentication
[2] https://github.com/buildbot/buildbot/pull/4763/files

Security: ada8db8a-8471-11e9-8170-0050562a4d7b

Approved by: ports-secteam (miwi)