Pysnc

- removed six typing, and cleaned up all other type returns
- fixed https://github.com/ServiceNow/PySNC/issues/78 -- more cleanly handled GlideElement
- fixed https://github.com/ServiceNow/PySNC/issues/75 -- fixed GlideAttachment API change/issue

* fix 72 to allow overriding request settings via environment, once again

left a print in -- oops

Missed a few things from a push i said i would do in the last release, and are in those release notes

* added batch api support, with update_multiple and delete_multiple
* added performance enhancements
* added support for extra long queries (over 23,000 characters)
* improved documentation
* added `GlideElement` support and associated functions, e.g. `gr.my_field.nil()`
* fixed pop_record's ability to update
* switched project to poetry over pipenv
* added tests
* improved feedback for some errors

- gh actions
- up default batch size for performance reasons
- improve attachment file handling (reading, mostly)
- improve documentation
- added jwt support