Fix for Tuition Repayment Plans

[mistergone]

This PR fixes a bug in tuition repayment plans by updating student-debt-calc to version 2.6.3. Also, it has been re-shrinkwrapped.

Changes

• student-debt-calc to version 2.6.3

Review

• @higs4281

Screenshots

The following summary is with a 2 year repayment term and a 1 year program length on a $37,764 tuition repayment plan with 0% interest. (Previously, 0% interest caused a bug which lead to "Estimated debt when repayment begins" incorrectly showing $0.)

Checklist

• [x] Changes are limited to a single goal (no scope creep)
• [x] Code can be automatically merged (no conflicts)
• [x] Code follows the standards laid out in the front end playbook
• [x] Passes all existing automated tests
• [x] New functions include new tests
• [x] New functions are documented (with a description, list of inputs, and expected output)
• [x] Placeholder code is flagged
• [x] Visually tested in supported browsers and devices
• [x] Project documentation has been updated (including the "Unreleased" section of the CHANGELOG)

[coveralls]

Coverage remained the same at 100.0% when pulling 873d6261469908ffdf9701de4d4590b7c2f70c52 on bug/trp into fa2aa5c0e6bec572c1d6f0695c99803b7b33bc5f on master.