chore: upgrade solidity-coverage to v0.6+

[sohkai]

Upgrades solidity-coverage.

A number of tests invoking the fallback function are now failing with an out of gas on the new version, likely due to new instrumentation rules. Previously they were operating within the limit, even under instrumentation.

cc @cgewecke

[coveralls]

Coverage decreased (-0.3%) to 99.265% when pulling 5706335 on upgrade-solidity-coverage into c85d34e on next.

[cgewecke]

@sohkai Taking a look today... send and transfer continue to fail on our tests as well even though the updated coverage client (6.4.5) uses a new vm option which should make instrumentation free. For example these tests at zeppelin run a gas check for ERC165 interfaces and seem ok.

[cgewecke]

@sohkai Could you retry with 0.6.2 when you have a chance? SC's send/transfer tests pass now and hopefully you can unskip all of yours as well.

Also left some notes about failing coverage jobs for aragon-apps at this issue thread in solidity-coverage.

[sohkai]

@cgewecke Can confirm with the new version that all the ETH transfers are working under coverage 🎉.

Thanks so much for helping out on this!

[facuspagnuolo]

Hell yea!!! 🤟🤟🤟🤟

[facuspagnuolo]

Let's create an issue to tackle the uncovered lines

[sohkai]

@facuspagnuolo Not sure why coverage decreased (if anything, not skipping those tests should increase it...), but we do have #514 for the few areas of coverage we previously missed :).

[izqui]

🙌🙌🙌