Can you add Shapes to the dependencies of your custom package

I'm trying to create a package of my tool, that uses Shapes inside of it. My knowledge is limited to this day of researching packaging and I hit a roadblock. I can't add "com.acegikmo.shapes": "4.1.3" to my dependencies of my package. Resulting in Unity telling me it can't find the Shapes namespace when I add the Assembly Definition file.

Shapes unwraps itself inside the Assets folder of the project, so packages can't know about it. https://docs.unity3d.com/Manual/upm-embed.html As stated under 3.

Is it simply not possible to add Shapes to a custom package? Or is my knowledge about packages to small and I'm doing something obviously wrong?