cuid v2.0.0

This release contains breaking changes, specifically the removal of functions
that were previously marked as deprecated. Please see the notes below for details.

Removed

• The top-level cuid(), slug(), and is_cuid() functions have been
  removed. These were implicitly yielding v1 CUIDs, and it is now required
  for CUID version to be explicitly specified.

  Importing cuid::v1::* or qualifying each function like v1::cuid() is
  equivalent to the removed top-level functions.

  In addition, version-specific top-level function names like cuid1(),
  cuid1_slug(), and is_cuid1() are provided.

This release also pulls in the following releases of the cuid1 and cuid2
subpackages:

• https://github.com/mplanchard/cuid-rust/releases/tag/cuid1-v0.1.1
• https://github.com/mplanchard/cuid-rust/releases/tag/cuid2-v0.1.5

These are both patch releases, with no interface-level changes.