Add linting to CI for Vyper files

[chriswessels]

Currently have linting for Python and Solidity files, but not Vyper.

Add linting support + hook up to Github workflows.

[fubuloubu]

Note: a tool doesn't exist for this yet, but it is possible to make one using Vyper's public API (which can output the AST)

[spinoch]

I'm looking into creating such a tool. Is there any chance for compensation in case it resolves this issue? (Not asking for specific numbers, but would be nice to get something)

[fubuloubu]

@spinoch yes! I think I can find some individuals that can put together a bounty if you are willing to help take this on!

[spinoch]

Cool. I'll see if I can come up with something by next week

[saltyfacu]

Hey @spinoch! It seems that you've done a lot of progress in the PR. Are you still working on it?

[spinoch]

Hey, @fameal . In short, no. We need to fix a few issues in the blackadder repo and I haven't had time lately. I still would like to get the issues fixed but I can't really give a time frame atm

[0xbeedao]

I have submitted a PR to fix this outstanding issue. #479

[pandadefi]

We need someone to build and maintain a linter. The linter should be able to work with multiple versions of vyper