Release google-cloud-storage 1.21.1

* Update storage class examples in docs and tests
  * Replace MULTI_REGIONAL and REGIONAL with STANDARD and NEARLINE.

[pr  googleapis#4069]

Release google-cloud-pubsub 1.0.0 (googleapis#4098)

* Allow wait to block for specified time
   * Add timeout argument to Subscriber#wait! method.
   * Document timeout argument on AsyncPublisher#wait! method.
 * Add stop! convenience method, calling both stop and wait
   * Add Subscriber#stop! method.
   * Add AsyncPublisher#stop! method.

Release google-cloud-bigquery 1.15.0 (googleapis#4035)

#### Features

 * Add Model encryption
   * Add Model#encryption
   * Add Model#encryption=
 * Add range support for Google Sheets
   * Add External::SheetsSource#range
   * Add External::SheetsSource#range=
 * Support use_avro_logical_types on extract jobs
   * Add ExtractJob#use_avro_logical_types?
   * Add ExtractJob::Updater#use_avro_logical_types=

Release google-cloud 0.62.0 (googleapis#4100)

#### Features

* Update google-cloud-pubsub dependency to 1.0

Release google-cloud-pubsub 0.39.3 (googleapis#4088)

#### Bug Fixes

* Fix Subscriber#wait! behavior
  * Fix an issue where the Subscriber#wait! would block
    for only 60 seconds, and not indefinitely.
  * This was introduced in the previous release, 0.39.2.

#### Configuration Changes

* Update Subscriber acknowledge and modify_ack_deadline configuration
  * The acknowledge and modify_ack_deadline RPCs have a lower size
    limit than the other RPCs. Requests larger than 524288 bytes will
    raise invalid argument errors.
* Update low-level client network configuration

Release google-cloud-pubsub 0.39.2 (googleapis#4026)

#### Bug Fixes

* Do not interrupt Subscriber callbacks when stopping
  * Allow in-process callbacks to complete when a Subscriber is stopped.

#### Documentation

* Update Subscriber stop and wait documentation
  * Update Subscriber#stop and Subscriber#wait! method

Release google-cloud-bigtable 0.6.1 (googleapis#3986)

#### Features

* Add IAM to low-level API client
  * Add BigtableTableAdminClient#get_iam_policy
  * Add BigtableTableAdminClient#set_iam_policy
  * Add BigtableTableAdminClient#test_iam_permissions

#### Documentation

* Update low-level IAM documentation
  * Update GetPolicyOption#requested_policy_version docs
  * Un-deprecate Policy#version

Release google-cloud-tasks 1.1.2 (googleapis#3985)

#### Documentation

* Update IAM documentation
  * Update GetPolicyOption#requested_policy_version docs
  * Un-deprecate Policy#version

Release google-cloud-spanner 1.10.1 (googleapis#3987)

#### Documentation

* Update low-level IAM documentation
  * Update GetPolicyOption#requested_policy_version docs
  * Un-deprecate Policy#version

Release google-cloud-security_center 0.3.2 (googleapis#3984)

#### Documentation

* Update IAM documentation
  * Update GetPolicyOption#requested_policy_version docs
  * Un-deprecate Policy#version