version of dependency doesn't update in node_modules if you change it in package.json

[miroslavaivanova]

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: 6.0.2

Describe the bug
Change a version of a dependency in a package.json and run the project. You will see that the version doesn't update in node_modules.

To Reproduce

1. tns create app --js
2. set nativescript-dev-webpack to be 1.0.1 in package.json and run app
3. You will see that the version in node_modules/nativescript-dev-webpack/package.json is 1.0.2

Expected behavior
version should update