v2.3.0

Update dependencies and support for py3.12 (end of 2023 upgrades) (#53)

* Upgrade numpy scipy astropy pandas jplephem matplotlib

* Remove poliastro

* Upgrade jplephem

* Remove AMAT.arrival, tests/test_arrival.py and references in docs

* Update ipykernel

* Set html_theme_options

* Delete checkpoint

* Fix intendation error in docs/source/installation.rst

* Update docs dependencies in docs/requirement.txt

* Pin jplephem==2.21 in docs/requirements.txt

* Update release to v2.3.0 in conf.py

* Updade pytest GitHub action to use py3.12

* Update .readthedocs.yml

* Update copyright

* Update python versions in setup.py