Pin prototbuf version

https://app.circleci.com/pipelines/github/pytorch/audio/10979/workflows/42005226-ca7e-471c-80f4-db09f4bd2089/jobs/692078

```
E   TypeError: Descriptors cannot not be created directly.
E   If this call came from a _pb2.py file, your generated code is out of date and must be regenerated with protoc >= 3.19.0.
E   If you cannot immediately regenerate your protos, some other possible workarounds are:
E    1. Downgrade the protobuf package to 3.20.x or lower.
E    2. Set PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION=python (but this will use pure-Python parsing and will be much slower).
E
E   More information: https://developers.google.com/protocol-buffers/docs/news/2022-05-06#python-updates
```

protocolbuffers/protobuf#10051
Lightning-AI/pytorch-lightning#13159

.circleci/unittest/linux/scripts/install.sh

@@ -70,7 +70,7 @@ fi
 (
     set -x
     conda install -y -c conda-forge ${NUMBA_DEV_CHANNEL} 'librosa>=0.8.0' parameterized 'requests>=2.20'
-    pip install kaldi-io SoundFile coverage pytest pytest-cov scipy transformers expecttest unidecode inflect Pillow sentencepiece pytorch-lightning
+    pip install kaldi-io SoundFile coverage pytest pytest-cov scipy transformers expecttest unidecode inflect Pillow sentencepiece pytorch-lightning 'protobuf<4.21.0'
 )
 # Install fairseq
 git clone https://github.com/pytorch/fairseq

.circleci/unittest/windows/scripts/install.sh

@@ -80,7 +80,8 @@ esac
         pytorch-lightning \
         scipy \
         transformers \
-        unidecode
+        unidecode \
+        'protobuf<4.21.0'
 )
 # Install fairseq
 git clone https://github.com/pytorch/fairseq