Log Message:
py-protobuf: updated to 3.7.0

version 3.7.0:
Python
* Added Python 3.7 compatibility.
* Modified ParseFromString to return bytes parsed .
* Introduce Proto C API.
* FindFileContainingSymbol in descriptor pool is now able to find field and enum \ 
values.
* reflection.MakeClass()  and  reflection.ParseMessage() are deprecated.
* Added DescriptorPool.FindMethodByName() method in pure python (c extension \ 
alreay has it)
* Flipped proto3 to preserve unknown fields by default.
* Added support for memoryview in python3 proto message parsing.
* Added MergeFrom for repeated scalar fields in c extension (pure python already \ 
has it)
* Surrogates are now rejected at setters in python3.
* Added public unknown field API.
* RecursionLimit is also set to max if allow_oversize_protos is enabled.
* Disallow duplicate scalars in proto3 text_format parse.
* Fix some segment faults for c extension map field.