fix: description file path

Author: kxxt

setup.cfg

@@ -4,7 +4,7 @@ version = 0.1
 author = Levi Zim
 author_email = [email protected]
 description = A simple text-to-speech client using azure TTS API(trial).
-long_description = file: README.md
+long_description = file: README.MD
 long_description_content_type = text/markdown
 url = https://github.com/kxxt/aspeak
 project_urls =