Fix flaky Assignment#summary_json test

[david-yz-liu]

Proposed Changes

(Describe your changes here. Also describe the motivation for your changes: what problem do they solve, or how do they improve the application or codebase? If this pull request fixes an open issue, use a keyword to link this pull request to the issue.)

There is a flaky test, e.g. see https://github.com/MarkUsProject/Markus/actions/runs/9433478827/job/25984461081. The cause was the non-deterministic ordering of a query. This PR fixes the test by enforcing a consistent order.

Screenshots of your changes (if applicable)

Associated [documentation repository](https://github.com/MarkUsProject/Wiki) pull request (if applicable)

Type of Change

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Type	Applies?
🚨 Breaking change (fix or feature that would cause existing functionality to change)
✨ New feature (non-breaking change that adds functionality)
🐛 Bug fix (non-breaking change that fixes an issue)
🎨 User interface change (change to user interface; provide screenshots)
♻️ Refactoring (internal change to codebase, without changing functionality)
🚦 Test update (change that only adds or modifies tests)	X
📦 Dependency update (change that updates a dependency)
🔧 Internal (change that only affects developers or continuous integration)

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[coveralls]

Pull Request Test Coverage Report for Build 9437015949

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
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• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 91.423%

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Totals
Change from base Build 9436790838:	0.0%
Covered Lines:	40000
Relevant Lines:	43079

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💛 - Coveralls