type: declare that yams ship type annotations

MANIFEST.in

@@ -6,6 +6,7 @@ include tox.ini
 include docs/*
 include test/*.py
 include test/data2/*.py
+include yams/py.typed
 recursive-include test/data *.sql *.rel *.esql *.py *.txt toignore
 recursive-include bin *
 prune debian

setup.py

@@ -53,6 +53,8 @@ setup(
     url=pkginfo["web"],
     classifiers=pkginfo.get("classifiers", []),
     packages=find_packages(exclude=["test*"]),
+    package_data={"yams": ["py.typed"]},
+    include_package_data=True,
     python_requires=">=3.6",
     install_requires=pkginfo.get("install_requires"),
     scripts=pkginfo.get("scripts", []),