fix: spelling errors in sorting criteria for query categories (#6173)

#### What type of PR is this?
/kind bug
/area core
/milestone 2.17.x

#### What this PR does / why we need it:
修复查询分类的排序条件拼写错误导致的错误

#### Which issue(s) this PR fixes:
Fixes #6171

#### Does this PR introduce a user-facing change?
```release-note
修复查询分类的排序条件拼写错误导致的错误
```

application/src/main/java/run/halo/app/theme/finders/impl/PostFinderImpl.java

@@ -165,7 +165,7 @@ public class PostFinderImpl implements PostFinder {
     private Flux<Category> listChildrenCategories(String categoryName) {
         if (StringUtils.isBlank(categoryName)) {
             return client.listAll(Category.class, new ListOptions(),
-                Sort.by(Sort.Order.asc("metadata.creationTimeStamp"),
+                Sort.by(Sort.Order.asc("metadata.creationTimestamp"),
                     Sort.Order.desc("metadata.name")));
         }
         return categoryService.listChildren(categoryName);