Consider using caret range for dependencies about solidity-coverage

[cgewecke]

Is there a particular reason why the version is pinned?

I don't think so - thanks for catching. #814 should fix this in the next patch. (Doing a little bit more work here this week and will republish when that's done).

@ChristopherDedominici Just to double-check did you have preference for pinning in #810?

[frangio]

My guess is @ChristopherDedominici just followed the previous convention:

[cgewecke]

Unfortunately he can't do that here - it's a minefield.