fix(mod): find outdated dependency correctly when updated one coexists

[hasundue]

• test: rename test/fixtures as test/data
• test: use deno.land/std for testing/mock.ts
• test(lib/update): add test cases
• fix(mod): find outdated dependency correctly when updated one coexists

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Comparison is base (67c2162) 84.58% compared to head (59c3549) 84.54%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #87 +/- ## ========================================== - Coverage 84.58% 84.54% -0.04% ========================================== Files 21 20 -1 Lines 824 822 -2 Branches 105 105 ========================================== - Hits 697 695 -2 Misses 126 126 Partials 1 1 ```

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