How to reproduce:
1. Create a new Unity project
2. Open the Package Manager
3. Make sure Advanced > Show dependencies is enabled
4. Select the Timeline package
5. See its dependencies

Expected result: Timeline is displayed to be using the built-in module Director
Actual result: Timeline does not display any dependencies

Reproducible with: 2019.3.7f1, 2020.1.0b3, 2020.2.0a4
Could not test with: 2017.4.38f1, 2018.4.19f1(Timeline package unavailable)

Reproducible with package versions: 1.0.0, preview.2 - 1.4.0

Notes:
Disabling the Director module causes a couple of Timeline errors to be thrown; they do indicate that Director must be enabled