Update to 1.40
    
    - New upstream release 1.40
      - Update to Devel::PPPort-3.52
      - Development perl is now 5.28.2
      - [csv2xlsx] sheetnames are restricted to 31 characters
      - Generate cpanfile
      - Add munge type "db"
      - [csv2xls/csv2xlsx] do not generate xls/xlsx on empty CSV (GH#18)
      - New: support $csv->formula (sub { ... })
      - Support stacked encodings
    - Use %{make_build} and %{make_install}