Fixes error message assertion in tests

[emmanuel-keller]

Thank you for submitting this pull request! We appreciate you spending the time to work on these changes.

What is the motivation?

Following this PR: surrealdb/surrealdb#5499
An error message used in a test assertion has been modified.

Type of Change

• 📚 Examples / docs / tutorials / dependencies update
• 🔧 Bug fix (non-breaking change which fixes an issue)
• 🥂 Improvement (non-breaking change which improves an existing feature)
• 🚀 New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to change)
• 🔐 Security fix

What does this change do?

Update the assertion.

What is your testing strategy?

Update an existing test.

Is this related to any issues?

surrealdb/surrealdb#5499

Have you read the Contributing Guidelines?

• I have read the Contributing Guidelines