removed -module-depth to support terraform 0.12

[jewee]

Description

-module-depth flag has been removed from terraform generated command as this is not supported anymore by latest version of terraform (0.12)

Related Issue

Related issue - #31

Motivation and Context

It is required in order to be able to execute code with terraform 0.12

How Has This Been Tested?

Tested by running ops terraform plan & apply with terraform 0.11 and 0.12

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[costimuraru]

Thanks for the contribution @jewee. Please sign the Contributor License Agreement (http://opensource.adobe.com/cla.html) and we can merge this.