Release rtflite 2.4.0 (#174)

* Run uv lock --upgrade

* Increment version number to 2.4.0

Author: nanxstats

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "rtflite"
-version = "2.3.1"
+version = "2.4.0"
 description = "Lightweight RTF composer for Python"
 authors = [
     { name = "Yilong Zhang", email = "elong0527@gmail.com" },