Fix decoding of MessagePack data

websocket-driver 0.8 changed the format in which it emits binary data
[1]:

> Emit binary message as a string with Encoding::BINARY instead of an array
> Add the option :binary_data_format to force the previous behaviour

[1] https://github.com/faye/websocket-driver-ruby/blob/main/CHANGELOG.md#080--2025-05-25

Author: lawrence-forooghian

ably.gemspec

@@ -25,7 +25,8 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency 'faraday-typhoeus', '~> 0.2.0'
   spec.add_runtime_dependency 'typhoeus', '~> 1.4'
   spec.add_runtime_dependency 'json'
-  spec.add_runtime_dependency 'websocket-driver', '~> 0.7'
+  # We disallow minor version updates, because this gem has introduced breaking API changes in minor releases before (which it's within its rights to do, given it's pre-v1). If you want to allow a new minor version, bump here and run the tests.
+  spec.add_runtime_dependency 'websocket-driver', '~> 0.8.0'
   spec.add_runtime_dependency 'msgpack', '>= 1.3.0'
   spec.add_runtime_dependency 'addressable', '>= 2.0.0'
 

lib/ably/realtime/connection/websocket_transport.rb

@@ -257,7 +257,7 @@ def parse_event_data(data)
         when :json
           JSON.parse(data)
         when :msgpack
-          MessagePack.unpack(data.pack('C*'))
+          MessagePack.unpack(data)
         else
           client.logger.fatal { "WebsocketTransport: Unsupported Protocol Message format #{client.protocol}" }
           data