CorrDiff: Fix bug in learning rate schedule

[mnabian]

Modulus Pull Request

Description

This fixes the unintended behavior in the warm-up learning rate if decay is smaller than 1

Checklist

• [x] I am familiar with the Contributing Guidelines.
• [x] New or existing tests cover these changes.
• [x] The documentation is up to date with these changes.
• [ ] The CHANGELOG.md is up to date with these changes.
• [ ] An issue is linked to this pull request.

Dependencies