TabControlStepper throws exception with MaterialDesignThemes 5.1.0

[CalebBe-2253]

Reproduction

In any app running MaterialDesignThemes 5.1.0 and MaterialDesignExtensions 3.3.0, attempt to use the TabControlStepper. Run application and encounter runtime exception

Minimum reproduction code: https://github.com/CalebBe-2253/MaterialDesignExtensionStepperIssue

It appears that this project needs to be updated to support MaterialDesignThemes 5 as there were some breaking changes regarding ShadowAssist

[CalebBe-2253]

I believe the solution to this particular issue with MaterialDesignThemes v5 is solved with a single line change to StepperTemplates.xaml