Fix build checks

[imalcolm1]

Description

WPF Store build:
The explicit target framework was causing an error when building the source generator as it only has the netstandard2.0 target framework. Forced the CatalogGenerator references to target netstandard2.0 on all projects.

Maui build check:
Was still targeting net9.0. It also had the same problem and solution as WPF with the CatalogGenerator TFM.

WinUI build check:
File path length was exceeded. Updated the action to specify a shorter clone path.

Type of change

• Bug fix

Platforms tested on

• WPF
• WinUI
• Maui Windows
• Maui Android
• Maui iOS
• Maui Catalyst

Checklist

• Self-review of changes
• All changes work as expected on all affected platforms
• There are no warnings related to changes
• Code is commented and follows .NET conventions and standards
• Codemaid and XAML styler extensions have been run on every changed file
• No unrelated changes have been made to any other code or project files
• Screenshots are correct size and display in description tab (800 x 600 on Windows, MAUI mobile platforms use the MAUI Windows screenshot)

[imalcolm1]

This change is not absolutely necessary given the later commit to force netstandard2.0 on the CatalogGenerator references, but the target framework is about to be outdated and not needed anyway