ns migrate does not update tsconfig file

[PeterStaev]

Environment
Provide version numbers for the following components (information can be retrieved by running tns info in your project folder or by inspecting the package.json of the project):

• CLI: 7.0.4

Describe the bug
I just run the migrate over a demo angular project of a plugin and no changes have been made in the tsconfig file of the app.

To Reproduce
Run ns migrate for a pre 7.0 project

Expected behavior
The migration should update the tsconfig to use the new required settings (like module: ESNext, target: es2015, etc.)

Sample project

Additional context