Update Digest-SHA to CPAN version 5.98

Update Digest-SHA to CPAN version 5.98

  [DELTA]

5.98  Wed Oct  4 00:40:02 MST 2017
  - removed "portable" mode from shasum and addfile
    -- rarely used, mostly in outdated systems
    -- potentially confusing features (e.g. \r\r\n -> \n)
    -- Universal Newlines mode (-U) a much cleaner approach
      -- mimics Universal Newlines in Python
  - shasum now uses Digest::SHA explicitly
    -- no longer loads Digest::SHA::PurePerl as an option
      -- hence no need for -R switch
    -- Digest::SHA::PurePerl has its own shasum: shasumpp