Fix opentelemetry-tools-google-cloud homepage URL (#111)

Current URL mentioned in PyPI website is referring to non-existing URL and returns 404. This corrects the URL to the corresponding page of the directory in the GitHub repository.

Author: ymotongpoo

opentelemetry-tools-google-cloud/setup.cfg

@@ -5,7 +5,7 @@ long_description = file: README.rst
 long_description_content_type = text/x-rst
 author = Google
 author_email = opentelemetry-pypi@google.com
-url = https://github.com/GoogleCloudPlatform/opentelemetry-operations-python/opentelemetry-tools-google-cloud
+url = https://github.com/GoogleCloudPlatform/opentelemetry-operations-python/tree/master/opentelemetry-tools-google-cloud
 platforms = any
 license = Apache-2.0
 classifiers =