Update to 3.0.2

CHANGELOG:
3.0.2
  * Tightened the upper bounds slightly to enable PVP compliance while
  retaining a flexible development cycle
  * Raised the upper bound on `contravariant`
3.0.1
  * Refactored directory layout
Haskell 98 bifunctors
Import bifunctors as wip/hs-bifunctors.