Agate-charts

-------------------------

* Add Python 3.12 support.
* Drop Python 3.7 support (end-of-life was June 27, 2023).

-----------------------

* Update to recent agate, matplotlib and Python versions.

--------------------------

* Use agate 0.10.0 extension API.
* TableSet.bar_chart
* TableSet.scatter_chart
* TableSet.column_chart
* TableSet.line_chart
* Table.bar_chart
* Table.scatter_chart
* Table.column_chart
* Table.line_chart