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

README.md

@@ -5,7 +5,7 @@ language:
 base_model:
 - answerdotai/ModernBERT-base
 base_model_relation: finetune
-pipeline_tag: sentence-similarity
+pipeline_tag: text-ranking
 library_name: transformers
 tags:
 - sentence-transformers