bernhard incompatible with protobuf 4.21.1

[anoopjb]

Versions

• Python 3.9.12
• protobuf - 3.2.0
• bernhard - 4.21.1

Steps to reproduce

• Install lastest version of protobuf, pip install protobuf==4.21.1
• Install bernhard, pip install bernhard
• Run an inline command to import bernhard, python -c "import bernhard", throws the error,

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "/usr/local/lib/python3.9/site-packages/bernhard/__init__.py", line 20, in <module>
    from . import pb
  File "/usr/local/lib/python3.9/site-packages/bernhard/pb.py", line 13, in <module>
    DESCRIPTOR = _descriptor.FileDescriptor(
  File "/usr/local/lib/python3.9/site-packages/google/protobuf/descriptor.py", line 1028, in __new__
    return _message.default_pool.AddSerializedFile(serialized_pb)
TypeError: expected bytes, str found

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