Description of changes

Move the postinstall script to be run as part of deprecate workflow where it is needed.
This was causing issues in windows environments where the script is not being executed as part of postinstall action.

Verified that the contents of the script or execute permissions aren't the issue.

Codegen Paramaters Changed or Added

Issue #, if available

Description of how you validated changes

Checklist

• PR description included
• yarn test passes
• Tests are changed or added
• Relevant documentation is changed or added (and PR referenced)
• Breaking changes to existing customers are released behind a feature flag or major version update
• Changes are tested using sample applications for all relevant platforms (iOS/android/flutter/Javascript) that use the feature added/modified
• Changes are tested on windows. Some Node functions (such as path) behave differently on windows.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.