fixing installation of orttraining nightly (#21547)
### Description
<!-- Describe your changes. -->
Changing ORT training installation steps
Current command for ORTtraining nightly installation was installing
stable version so creating a fix for this.
### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->
Current command for ORTtraining nightly installation was installing
stable version so creating a fix for this.
