Remove duplicate "skipped test" instruction

[MaoShizhong]

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Because

Removing this was missed in #509 presumably because it wasn't expected for this exercise to repeat the "skipped tests" info.

This PR

• Removes redundant "skipped tests" paragraph from exercise 7's instructions.

Issue

Closes #542

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. 01_helloWorld: Update test cases
• 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 any changes that affect the solution of an exercise, I've also updated the solution in the /solutions folder