**Feature summary**:
Find a new sse client package for Eventstreams. Possible options:
- [[ https://pypi.org/project/sseclient-py/ | sseclient-py ]]
- [[https://pypi.org/project/aiohttp-sse-client| aiohttp-sse-client ]]
- Support our own sse client which has the benefit that their usage does not depend on a virtual environment installation on toolforge (where sseclient isn't preinstalled)
**Reason**:
Currently we use [[ https://pypi.org/project/sseclient/ | sseclient ]] packages for EventStreams but we had to pin its version to < 0.0.23 in rPWBC3babbc5 due to T222885. This packages is [[ https://github.com/btubbs/sseclient/commit/87e4b49b052b538b4d8dfc4db75ca87f6757119d | not activly maintained ]] and the patch for T222885 ([[ https://github.com/btubbs/sseclient/issues/28 | issue 28]]) is [[ https://github.com/btubbs/sseclient/pull/35 | is pending for 3 years ]] and other improvements aren't available.