Jsonmerge

* Fix failing tests with jsonschema>=4.18.0.

* Require jsonschema 4.17.3 or earlier since some tests currently fail
with 4.18.0 and later releases.

* Add sortByRef and sortReverse options for the append and
arrayMergeById strategies.
* Fix failing tests with jsonschema>=4.15.0.
* Fix warning about iter_errors use that was deprecated around
jsonschema 4.10.1.
* Drop support for jsonschema<=2.4.0.

* Allow "idRef" option for arrayMergeById strategy to be an array of
pointers.
* Warn that "meta" argument is deprecated.

* Add "merge_options" argument to the Merger.merge method, a more
generic replacement for the "meta" argument. "meta" argument still
works, however its use is now deprecated and it may be removed in a
future release. Third-party code that subclasses the Strategy class
and depends on the "meta" argument may need to be updated.
* Add arrayMergeByIndex merge strategy.

* Fix assertion failure when object contains a float NaN value.