v8.15.2

ModelingToolkit v8.15.2

Diff since v8.15.1

Closed issues:

• Handling of null differential equations (#1654)
• connect doesn't support units? (#1655)

Merged pull requests:

• WIP: Add linearize function (#1675) (@YingboMa)
• add option to access state bounds (#1679) (@baggepinnen)
• Throw a more concrete error on unsupported modelingtoolkitize parameters (#1682) (@ChrisRackauckas)