Modernize

[lehins]

This PR takes care of some minor issues that I've ran into that are a result of either newer ghc or newer dependency

Also usage of unsafeSTToPrim was uncalled for, there was nothing unsafe there. Switched to stToPrim

This PR discovered some sort of linker issue with doctests on newer MacOS, which unfortunately I have no idea how to fix:

System/Random/MWC.hs:30: failure in expression `g <- createSystemRandom'
expected: 
 but got: ld: warning: -undefined dynamic_lookup may not work with chained fixups
          ^

Examples: 33  Tried: 8  Errors: 0  Failures: 1