CI-testing failed because of protobuf

[WenjieDu]

Issue description

I notice that we're having some tasks failed in our CI-testing workflow, for example, https://github.com/WenjieDu/PyPOTS/actions/runs/5064524248/jobs/9092539446.

/usr/share/miniconda/envs/pypots-test/lib/python3.8/site-packages/google/protobuf/descriptor.py:51: in <module>
    from google.protobuf.pyext import _message
E   ImportError: /usr/share/miniconda/envs/pypots-test/lib/python3.8/site-packages/google/protobuf/pyext/_message.cpython-38-x86_64-linux-gnu.so: undefined symbol: _ZN6google8protobuf2io17SafeDoubleToFloatEd

I have investigated this error and it has nothing to do with code in PyPOTS. The issue source is that these failed jobs have their conda installing a newer version of protobuf which is not compatible with other dependencies. It can be directly solved by specifying the version of protobuf as 4.21.12, and I have tested it.