chore(deps): specify `PyPNG` as a dependency
diff --git a/pyproject.toml b/pyproject.toml
index 14684f3..c61f1a5 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -20,6 +20,9 @@
     "python-youtube~=0.8.0",
     "taxjar~=1.9.2",
     "tweepy~=3.10.0",
+
+    # Not used directly - required by PyQRCode for PNG generation
+    "pypng~=0.20220715.0",
 ]
 
 [build-system]