Fix requires-python to be compatible with all 3.8 versions (#1027)

Author: BenRKarl

pyproject.toml

@@ -21,7 +21,7 @@ name = "google-ads"
 version = "28.0.0.post2"
 description = "Client library for the Google Ads API"
 readme = "./README.rst"
-requires-python = "==3.8"
+requires-python = "==3.8.*"
 license = { file = "LICENSE" }
 
 authors = [