Fixes a typo in debugging_exercises

[noxarad]

Because

Typos are the devil!

This PR

• Changes 'occured' to 'occurred'.

Issue

Didn't find any open pull requests or issues.

Additional Information

Pull Request Requirements

• I have thoroughly read and understand The Odin Project Contributing Guide
• The title of this PR follows the location of change: brief description of change format, e.g. Data types exercise: Update spec files
• 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 this PR includes changes to exercises, they are also changed in the solutions folder.

[rlmoser99]

Thank you for taking the time to fix this spelling error