Release ansys-sphinx-theme v1.4

[jorgepiloto]

This new minor release of our corporate theme for Sphinx has the following goals:

• Migrate to the sphinx-theme-builder
• Clean unnecessary asset files
• Revisit dangling issues
• Provide Plotly support for sphinx-gallery

[MaxJPRey]

@jorgepiloto Thanks for listing the outcomes expected for the next minor release.