Update Spanner library version and add proto lib API surface (#2198) (#2201)
Update Spanner library version and add proto lib API surface (#2198) (#2201)

Co-authored-by: Daniel Zou <8ba4a3675dc47c3249b65fdff0318a8661d1ecb2@users.noreply.github.com>
GoogleCloudPlatform/cloud-opensource-java,GoogleCloudPlatform/cloud-opensource-java,GoogleCloudPlatform/cloud-opensource-java