3.13
Clear cyclic references in the parser and the emitter to avoid extra GC calls.
Raise an error when test suite failed.
Fixed handling --verbose flag in the test appliance.
Share data files between Py2 and Py3 test suites.
Fixed a problem when CDumper incorrectly serializes a node anchor.
Fixed tests on the Windows platform.
Fixed emitting of invalid BOM for UTF-16.
Use Cython if available; added Python 3 support to _yaml.pyx.
Fixed str/bytes issues with Python 3 in _yaml.pyx.