DRP and ICS have conflicting requirements for {{attrs}} package version

The DRP stack has pinned pytest 3.6.2 (from 2018-07), which requires attrs < 19.2.0.

ICS (and thus ics_drpActor) requires a modern twisted library, which requires attrs >= 19.2.0

At the next level of detail, 19.2.0 removed a deprecated alias attr.ib(convert=) for attr.ib(converter=), which pytest 3.6.2 uses in one place. pytest 3.6.3 fixes that.

And 19.2.0 introduced a new attrs argument which twisted now uses: attr.s(eq=).

attrib and attrs look like a pain to monkey patch. For now I have renamed the one call in the installed pytest at Subaru.