GCP kms not working it latest gems

[rcalosso]

Environment

Provide at least:

• Ruby Version.
• 2.7.2
• Symmetric Encryption Version.
• 4.3.0
• Application/framework names and versions (e.g. Rails, Sinatra, Puma, etc.).
• Rails
• Full Stack Trace, if an exception is being raised.
• bundle exec symmetric-encryption --generate --keystore gcp --app-name Sample --environments "production"
  bundler: failed to load command: symmetric-encryption (/opt/narvar/vendor/bundle/ruby/2.7.0/bin/symmetric-encryption)
  NameError: uninitialized constant Google::Cloud::Kms::V1::KeyManagementServiceClient
  /opt/narvar/vendor/bundle/ruby/2.7.0/gems/symmetric-encryption-4.3.0/lib/symmetric_encryption/keystore/gcp.rb:67:in client' /opt/narvar/vendor/bundle/ruby/2.7.0/gems/symmetric-encryption-4.3.0/lib/symmetric_encryption/keystore/gcp.rb:59:in encrypt'
  /opt/narvar/vendor/bundle/ruby/2.7.0/gems/symmetric-encryption-4.3.0/lib/symmetric_encryption/keystore/gcp.rb:45:in write' /opt/narvar/vendor/bundle/ruby/2.7.0/gems/symmetric-encryption-4.3.0/lib/symmetric_encryption/keystore/gcp.rb:18:in generate_data_key'
  /opt/narvar/vendor/bundle/ruby/2.7.0/gems/symmetric-encryption-4.3.0/lib/symmetric_encryption/keystore.rb:24:in block in generate_data_keys' /opt/narvar/vendor/bundle/ruby/2.7.0/gems/symmetric-encryption-4.3.0/lib/symmetric_encryption/keystore.rb:18:in each'
  /opt/narvar/vendor/bundle/ruby/2.7.0/gems/symmetric-encryption-4.3.0/lib/symmetric_encryption/keystore.rb:18:in generate_data_keys' /opt/narvar/vendor/bundle/ruby/2.7.0/gems/symmetric-encryption-4.3.0/lib/symmetric_encryption/cli.rb:222:in generate_new_config'
  /opt/narvar/vendor/bundle/ruby/2.7.0/gems/symmetric-encryption-4.3.0/lib/symmetric_encryption/cli.rb:66:in run!' /opt/narvar/vendor/bundle/ruby/2.7.0/gems/symmetric-encryption-4.3.0/lib/symmetric_encryption/cli.rb:14:in run!'
  /opt/narvar/vendor/bundle/ruby/2.7.0/gems/symmetric-encryption-4.3.0/bin/symmetric-encryption:5:in <top (required)>' /opt/narvar/vendor/bundle/ruby/2.7.0/bin/symmetric-encryption:23:in load'
  /opt/narvar/vendor/bundle/ruby/2.7.0/bin/symmetric-encryption:23:in `<top (required)>'

Expected Behavior

Expect to generate config file

Actual Behavior

Stack trace, crash cause module / class name is wrong

Pull Request

Will work on PR, but looks like line 67 above is missing ::, should read

self.class::KMS::KeyManagementService::Client.new(timeout: 2, credentials: credentials)

[reidmorrison]

If Google have changed their API, when you submit the PR, please verify that the new changes are backward compatible with the previous Google API version.