fix: compartor exception in post list

[guqing]

What type of PR is this?

/kind bugfix
/area core

What this PR does / why we need it:

修复文章列表查询时的类型转换错误

文章列表查询将 collectList 错写为 collectSortedList 导致此 Contributor cannot be cast to class java.lang.Comparable，
collectSortedList 会使用 Arrays.sort(a, (Comparator) c)，这需要目标类实现 Comparable 才行，而此处并不需要自然排序。

Which issue(s) this PR fixes:

Fixes #2830

Special notes for your reviewer:

此 bug 的复现方式为：
编辑一篇文章保存后，在使用另一个用户账户编辑此文章并发布就会出现，而使用此 PR 后问题消失，此问题只对 Contributor 这个类型有效它不是自定义模型类，而 Tag 和 Category 都是自定义模型 继承了 AbstractExtension 而它 实现了 Comparable 接口。

/cc @halo-dev/sig-halo

Does this PR introduce a user-facing change?

修复文章列表查询时的类型转换错误

[f2c-ci-robot]

@guqing: The label(s) kind/bugfix cannot be applied, because the repository doesn't have them.

In response to this:

What type of PR is this?

/kind bugfix
/area core

What this PR does / why we need it:

修复文章列表查询时的类型转换错误

文章列表查询将 collectList 错写为 collectSortedList 导致此 Contributor cannot be cast to class java.lang.Comparable，
collectSortedList 会使用 Arrays.sort(a, (Comparator) c)，这需要目标类实现 Comparable 才行，而此处并不需要自然排序。

Which issue(s) this PR fixes:

Fixes #2830

Special notes for your reviewer:

/cc @halo-dev/sig-halo

Does this PR introduce a user-facing change?

修复文章列表查询时的类型转换错误

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[guqing]

/kind bug

[ruibaby]

成功复现，并通过此 PR 测试可以成功修复。

/lgtm

[JohnNiang]

/approve

[f2c-ci-robot]

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