(v2) Add missing dependency packaging at min version 21

The recent switch from setup.py to pyproject.toml omitted dependency `packaging`

Fixes: #2085

Author: chrisinmtown

pyproject.toml

@@ -54,6 +54,7 @@ inflection = ">= 0.3.1"
 Jinja2 = ">= 3.1.2"
 jsonschema = ">= 4.17.3"
 MarkupSafe = ">= 3.0.2"
+packaging = ">= 21"
 python-multipart = ">= 0.0.15"
 PyYAML = ">= 5.1"
 requests = ">= 2.27"