fix: add packaging as explicit dependency (#7)

The packaging library is used in kagan/cli/update.py for version parsing
but was not declared as a runtime dependency. This caused
ModuleNotFoundError when running kagan installed from PyPI on systems
where packaging was not already present as a transitive dependency.

Author: aorumbayev

pyproject.toml

@@ -34,6 +34,7 @@ dependencies = [
     "click>=8.1.0",
     "httpx>=0.27.0",
     "pyperclip>=1.11.0",
+    "packaging>=24.0",
 ]
 
 [project.scripts]