fix: add py.typed marker

This will remove any mypy error of packages using the SDK. This simply
marks that this package support type annotations, which is already true.

Author: cjumel

linkup/py.typed

@@ -27,6 +27,7 @@
     ],
     keywords="linkup api sdk client search",
     packages=find_packages(),
+    package_data={"linkup": ["py.typed"]},
     python_requires=">=3.8",
     install_requires=[
         "httpx",