Log Message:
py-google-api-core: updated to 1.20.0

1.20.0:

Features
allow disabling response stream pre-fetch

1.19.1:

Bug Fixes
bump up grpcio minimum version to 1.29.0

1.19.0:

Features
client_options: add new client options 'quota_project_id', 'scopes', and \ 
'credentials_file'

1.18.0:

Features
[CBT-6 helper] Exposing Retry._deadline as a property
add client_encryped_cert_source to ClientOptions
AsyncIO Integration [Part 2]
First batch of AIO integration
third batch of AsyncIO integration

1.17.0:

Features
api_core: add retry param into PollingFuture() and it's inheritors
api-core: add client_cert_source to ClientOptions

Bug Fixes
consume part of StreamingResponseIterator to support failure while under a retry \ 
context