Fix for RPC-attaching to a dockerized ganache in OSX.

[mariuspod]

What I did

I've fixed the bug where OSX clients would get a psutil.AccessDenied exception when connecting to a dockerized ganache without sudo.

Fixes #992

How I did it

I've added an extra check for the platform.system() to handle OSX clients a bit differently due to the open issue in psutils: giampaolo/psutil#1219

Instead of querying all available network connections, I'm searching for the com.docker.backend process and attach to that. Added some tests for it as well.

How to verify it

On a mac run:

docker run -p 8545:8545 trufflesuite/ganache-cli

and then in another terminal:

brownie console

Checklist

• I have confirmed that my PR passes all linting checks
• I have included test cases
• I have updated the documentation
• I have added an entry to the changelog

[iamdefinitelyahuman]

Sorry, the recent merge of #998 likely caused a bunch of conflcts here 😬

[mariuspod]

No worries, I've rebased to master and added some tests to it.

Now I hope that all workflows become green 🤖

[mariuspod]

build failed :-(
it seems it has to do something with the changed handling of StopIteration from python-3.8:
https://www.python.org/dev/peps/pep-0479/
need to refactor it a bit...

[mariuspod]

Made it backwards-compatible so we have code handling python-3.6 and newer versions which don't raise StopIteration in some generators anymore. Luckily, we have github workflows for different python versions so this issue came up 👍

[iamdefinitelyahuman]

🙏