Update `deckar01-task_list` gem to fix unrecognized task item

What does this MR do?

A pull request was merged that fixes the issue where a task item that has no text except spaces would get incorrectly recognized as a task item on the front end but would not on the backend. CommonMarker does not recognize such lines as valid task items.

Related issue: #30182 (closed)

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Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

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• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
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