fix setup.py for new publish workflow

Author: arthanson

setup.py

@@ -11,7 +11,7 @@
     use_scm_version=True,
     setup_requires=["setuptools_scm"],
     packages=find_packages(exclude=["tests", "tests.*"]),
-    long_description=open('README.md').read(),
+    long_description=(this_directory / "README.md").read_text(),
     long_description_content_type='text/markdown',
     install_requires=[
         "requests>=2.20.0,<3.0",