Log Message:
libplist: update to 2.2.0.

Version 2.2.0
~~~~~~~~~~~~~

- Changes:
  * bplist: Improve recursion check performance by at least 30% for large files
  * test: Fix test suite on Windows
  * cython: Fix handling of Date nodes (MACH_EPOCH)
  * Add new plist_*_val_compare(), plist_*_val_contains() helper functions
  * Fix/suppress several compiler warnings
  * plistutil: Added ability for files to be read from stdin
  * plistutil: Added ability to specify output format
  * Fix: Return NULL from plist_copy() if passed a NULL pointer instead of asserting
  * Add GitHub Actions integration for automatic build tests
  * plistutil: Add manual page and usage output
  * Fix removal of docs directory on `make clean`
  * Improve README.md with project description, installation, contributing and
    usage sections
  * Rename library and all related files by adding an API version resulting
    in "libplist-2.0" and "libplist++-2.0"