Log Message:
devel/fourmolu: Update to 0.15.0.0

Fourmolu 0.15.0.0
    * Add single-deriving-parens configuration option to determine if
      deriving clauses of a single type should be parenthesized (#386)
    * Fix the order in which the configurations are applied (#390)

Upstream changes:
Ormolu 0.7.4.0
    * Don't error when the JavaScriptFFI language pragma is present. Issue
      1087.
    * Improve comment placement in if-then-else blocks. Issue 998.
    * Now command line options for fixity overrides and module re-exports
      overwrite information from .ormolu files. Issue 1030.
    * Respect newlines in data declarations in more cases. Issue 1077 and
      issue 947.
    * The -d / --debug command line option now makes Ormolu print out debug
      information regarding operator fixity inference. Issue 1060.