Update README.md (#888)
Update README.md (#888)

Removing obsolete/invalid pip instructions.
The gsuite-grant-analyzer does not exist on pypi.org, and is therefore a security risk.

GoogleCloudPlatform/professional-services,GoogleCloudPlatform/professional-services,GoogleCloudPlatform/professional-services,GoogleCloudPlatform/professional-services,GoogleCloudPlatform/professional-services,GoogleCloudPlatform/professional-services,GoogleCloudPlatform/professional-services,GoogleCloudPlatform/professional-services,GoogleCloudPlatform/professional-services