Add pipeline tag

This PR improves the model card's metadata by adding the `pipeline_tag`, ensuring people can find your model at https://huggingface.co/models?pipeline_tag=text-to-audio

README.md

@@ -2,14 +2,15 @@
 language:
 - zh
 - en
+library_name: DiffRhythm
+license: other
+license_name: stable-audio-community
+license_link: LICENSE
 tags:
 - music
 - art
 - diffusion
-license: other
-license_name: stable-audio-community
-license_link: LICENSE
-library_name: DiffRhythm
+pipeline_tag: text-to-audio
 ---
 
 <p align="center">