Explicitly add py.typed for setuptools

Author: oschwald

pyproject.toml

@@ -38,6 +38,9 @@ Documentation = "https://maxminddb.readthedocs.org/"
 "Source Code" = "https://github.com/maxmind/MaxMind-DB-Reader-python"
 "Issue Tracker" = "https://github.com/maxmind/MaxMind-DB-Reader-python/issues"
 
+[tool.setuptools.package-data]
+maxminddb = ["py.typed"]
+
 [tool.black]
 # src is showing up in our GitHub linting builds. It seems to
 # contain deps.