Client CPP 4.0.0

What's Changed

• Support get the producer name of a message by @BewareMyPower in https://github.com/apache/pulsar-client-cpp/pull/524
• Bump the C++ standard to 17 by @BewareMyPower in https://github.com/apache/pulsar-client-cpp/pull/525
• [fix][ProtobufNativeSchema] Fix build by converting abseil string_view to std::string by @dannf in https://github.com/apache/pulsar-client-cpp/pull/527
• Support getting encryption context on a message by @BewareMyPower in https://github.com/apache/pulsar-client-cpp/pull/526

New Contributors

• @dannf made their first contribution in https://github.com/apache/pulsar-client-cpp/pull/527

Full Changelog: https://github.com/apache/pulsar-client-cpp/compare/v3.8.0...v4.0.0