genie_python: review obsolete packages

[FreddieAkeroyd]

Now support for python 2.7 has been dropped, we should review requirements.txt for any unnecessary additions as these can cause issues e.g. enum34 caused problems on python startup on ESS daq linux machine. Do we need backports, 2to3, six, ...

Acceptance criteria

• Figure out what each requirement is used for
• Unnecessary modules removed
• It is obvious from the release notes what we have removed

[FreddieAkeroyd]

Maybe do during #6370 ?

[rerpha]

Was just about to suggest this!

[rerpha]

Follows on from #6132

[DominicOram]

As we do this we should try and document what each dependency is for and why it is there, probably jut as comments in the requirements.txt. I think we have got a lot of stuff in there that people have just thrown in.

[rerpha]

As we do this we should try and document what each dependency is for and why it is there, probably jut as comments in the requirements.txt. I think we have got a lot of stuff in there that people have just thrown in.

or better yet, we make separate requirements.txts for each repository that requires special dependencies, even if they are stored in genie python itself. You can create requirements files with custom names and then include them in a parent requirements.txt like this - https://stackoverflow.com/questions/17803829/how-to-customize-a-requirements-txt-for-multiple-environments

[rerpha]

so for example we have a bskafka-requirements.txt which means we can pull anything kafka and flatbuffers out of the main requirements.txt

[DominicOram]

Yes, e.g. #5426

[Tom-Willemsen]

Substantially similar issue in other repo. genie itself no longer has these requirements (or any others that it doesn't directly use)