Prisma ORM lesson: fix broken link in assignment

[blue0206]

Prisma ORM lesson: Fix broken link for "Data migration" guide in assignment

Because

The link to the "Data migration" page was broken because the page has been moved to a new href.

This PR

• Fixed the link for "Data Migration" guide in assignment.

Issue

Couldn't find any existing issue/PR regarding this fix.

Additional Information

Pull Request Requirements

• I have thoroughly read and understand The Odin Project curriculum contributing guide
• The title of this PR follows the location of change: brief description of change format, e.g. Intro to HTML and CSS lesson: Fix link text
• The Because section summarizes the reason for this PR
• The This PR section has a bullet point list describing the changes in this PR
• If this PR addresses an open issue, it is linked in the Issue section
• If any lesson files are included in this PR, they have been previewed with the Markdown preview tool to ensure it is formatted correctly
• If any lesson files are included in this PR, they follow the Layout Style Guide

[rlmoser99]

Thank you for taking the time to update this link!

[blue0206]

Thank you for merging my first PR 😄