Declare packaging as a dependency

plugwise/__init__.py and helper.py import packaging, but it was not in
dependencies, so import plugwise failed on a clean install.

Author: Kayvan-Zahiri

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## Ongoing
+
+- Declare `packaging` as a dependency; `import plugwise` failed on a clean install without it
+
 ## v1.14.7
 
 - Adapt to percentages being shown as 0-100 instead of 0-1, solving Issue [#903](https://github.com/plugwise/python-plugwise/issues/903)

pyproject.toml

@@ -30,6 +30,7 @@ dependencies    = [
         "aiohttp>=3.14",
         "defusedxml",
         "munch",
+        "packaging",
         "python-dateutil",
 ]