Update model metadata to set pipeline tag to the new `text-ranking`

Hello!

## Pull Request overview
* Update metadata to set pipeline tag to the new `text-ranking`

## Changes
This is an automated pull request to update the metadata of the model card. We recently introduced the [`text-ranking`](https://huggingface.co/models?pipeline_tag=text-ranking) pipeline tag for models that are used for ranking tasks, and we have a suspicion that this model is one of them.

Feel free to respond if you have questions or concerns.

- Tom Aarsen

README.md

@@ -1,5 +1,6 @@
 ---
 base_model:
 - klue/roberta-small
+pipeline_tag: text-ranking
 ---
 업스테이지 "과학 지식 질의 응답 시스템 구축" 대회와 관련된 데이터로 학습함.