Fix the framework helper method in the github advisory sync

[kiskoza]

I was reading the repo's code after a recent contribution (out of curiosity) and I've found one very strange method for the Github Advisory sync process. I wasn't sure what it should do, as it made no sense, it returned nil regardless of its (implicit) inputs. So I did a bit more investigation and found that it meant to mark some vulnerabilities to be part of a framework, but it was lost over time. The history of the method looks like this:

• The method was written ages ago.
• Fixed framework field method to work - which fixed 11 existing advisories #652 did a cosmetic refactor by removing surrounding %[] from the case-when conditions
• Add "jquery-rails" as a candidate to add "framework: rails" during sync script run  #681 added a new gem to the condition list - and assumed that there were a missing comma, which turned the returned value (rails) to be part of the condition list

Not sure if I need to re-run anything to backfill the framework data or anything like that, but I'm happy to do that if it helps, just let me know.