fix: category and tag query parameters in post query (#2441)

#### What type of PR is this?
/kind api-change
/kind improvement
/area core
/milestone 2.0
#### What this PR does / why we need it:
修复文章列表的分类、标签查询参数方法名和取值不一致导致无效问题
#### Which issue(s) this PR fixes:

Fixes #2439

#### Special notes for your reviewer:
/cc @halo-dev/sig-halo 
#### Does this PR introduce a user-facing change?

```release-note
None
```

src/main/java/run/halo/app/content/PostQuery.java

@@ -1,5 +1,6 @@
 package run.halo.app.content;
 
+import io.swagger.v3.oas.annotations.media.Schema;
 import java.util.List;
 import java.util.Set;
 import org.springframework.lang.Nullable;
@@ -20,16 +21,19 @@ public class PostQuery extends IListRequest.QueryListRequest {
     }
 
     @Nullable
+    @Schema(name = "contributor")
     public Set<String> getContributors() {
         return listToSet(queryParams.get("contributor"));
     }
 
     @Nullable
+    @Schema(name = "category")
     public Set<String> getCategories() {
         return listToSet(queryParams.get("category"));
     }
 
     @Nullable
+    @Schema(name = "tag")
     public Set<String> getTags() {
         return listToSet(queryParams.get("tag"));
     }