devel/ruby-zeitwerk: update to 2.6.0

2.6.0 (13 June 2022)

* Directories are processed in lexicographic order.

  Different file systems may list directories in different order, and with
  this change we ensure that client code eager loads consistently across
  platforms, for example.

* Before this release, subdirectories of root directories always represented
  namespaces (unless ignored or collapsed).  From now on, to be considered
  namespaces they also have to contain at least one non-ignored Ruby file
  with extension .rb, directly or recursively.

  If you know beforehand a certain directory or directory pattern does not
  represent a namespace, it is intentional and more efficient to tell
  Zeitwerk to ignore it.

  However, if you don't do so and have a directory tasks that only contains
  Rake files, arguably that directory is not meant to represent a Ruby
  module.  Before, Zeitwerk would define a top-level Tasks module after it;
  now, it does not.

  This feature is also handy for projects that have directories with
  auxiliary resources mixed in the project tree in a way that is too
  dynamic for an ignore pattern to be practical.  See #216.

  In the unlikely case that an existing project has an empty directory for
  the sole purpose of defining a totally empty module (no code, and no
  nested classes or modules), such module has now to be defined in a file.

  Directories are scanned again on reloads.

* On setup, loaders created with Zeitwerk::Loader.for_gem issue warnings if
  lib has extra, non-ignored Ruby files or directories.

  This is motivated by existing gems with directories under lib that are not
  meant to define Ruby modules, like directories for Rails generators, for
  instance.

  This warning can be silenced in the unlikely case that the extra stuff is
  actually autoloadable and has to be managed by Zeitwerk.

  Please, check the documentation for further details.

  This method returns an instance of a private subclass of Zeitwerk::Loader
  now, but you cannot rely on the type, just on the interface.

(taca)