Compatibility with random-fu 3.0

[sternenseemann]

Build log with the latest version of random-fu:

Building library for random-extras-0.19..
[1 of 5] Compiling Data.Random.Distribution.Uniform.Exclusive ( Data/Random/Distribution/Uniform/Exclusive.hs, dist/build/Data/Random/Distribution/Uniform/Exclusive.o, dist/build/Data/Random/Distribution/Uniform/Exclusive.dyn_o )
[2 of 5] Compiling Data.Random.Dovetail ( Data/Random/Dovetail.hs, dist/build/Data/Random/Dovetail.o, dist/build/Data/Random/Dovetail.dyn_o )

Data/Random/Dovetail.hs:42:1: warning: [-Wunused-imports]
    The import of ‘Control.Applicative’ is redundant
      except perhaps to import instances from ‘Control.Applicative’
    To import instances alone, use: import Control.Applicative()
   |
42 | import Control.Applicative ((<$>))
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[3 of 5] Compiling Data.Random.Extras ( Data/Random/Extras.hs, dist/build/Data/Random/Extras.o, dist/build/Data/Random/Extras.dyn_o )
[4 of 5] Compiling Data.Random.Show.Unsafe ( Data/Random/Show/Unsafe.hs, dist/build/Data/Random/Show/Unsafe.o, dist/build/Data/Random/Show/Unsafe.dyn_o )

Data/Random/Show/Unsafe.hs:24:40: error:
    • Could not deduce (random-1.2.1:System.Random.Internal.StatefulGen
                          DevRandom IO)
        arising from a use of ‘runRVar’
      from the context: Show a
        bound by the instance declaration
        at Data/Random/Show/Unsafe.hs:23:10-34
    • In the second argument of ‘($)’, namely ‘runRVar rv DevURandom’
      In the expression: show . unsafePerformIO $ runRVar rv DevURandom
      In an equation for ‘show’:
          show rv = show . unsafePerformIO $ runRVar rv DevURandom
   |
24 |     show rv = show . unsafePerformIO $ runRVar rv DevURandom
   |                                        ^^^^^^^^^^^^^^^^^^^^^
[5 of 5] Compiling Data.Random.Shuffle.Weighted ( Data/Random/Shuffle/Weighted.hs, dist/build/Data/Random/Shuffle/Weighted.o, dist/build/Data/Random/Shuffle/Weighted.dyn_o )

Data/Random/Shuffle/Weighted.hs:49:1: warning: [-Wunused-imports]
    The import of ‘Control.Applicative’ is redundant
      except perhaps to import instances from ‘Control.Applicative’
    To import instances alone, use: import Control.Applicative()
   |
49 | import Control.Applicative ((<$>))
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^