Log Message:
devel/ruby-zeitwerk: update to 2.6.15

2.6.14 (2024-05-14)

* Implements Zeitwerk::Loader#all_expected_cpaths, which returns a hash that
  maps the absolute paths of the files and directories managed by the
  receiver to their expected constant paths.

* Please, check its documentation for further details.

2.6.15 (2024-05-26)

* Internal improvements.