protobuf 3.16.0

Google's language-neutral, platform-neutral, extensible mechanism for serializing structured data.

https://developers.google.com/protocol-buffers/

License: BSD-3-Clause

Changes

* read_property() handler is not supposed to return NULL (#8362)
* Changed parameter type from long to integer (#7613)
* fix: README supported PHP version for C extension (#8236)