Fix library_name

Follow-up after https://huggingface.co/openbmb/VoxCPM-0.5B/discussions/4

To be aligned with https://github.com/huggingface/huggingface.js/pull/1755 (and naming convention), the library_name should be lowercased.

README.md

@@ -6,7 +6,7 @@ language:
 base_model:
 - openbmb/MiniCPM4-0.5B
 pipeline_tag: text-to-speech
-library_name: VoxCPM
+library_name: voxcpm
 tags:
 - text-to-speech
 - speech