Downgrade protobuf to version 4

Add upper bound of ansys_tools_protoc_helper to < 0.7.0.
ansys_tools_protoc_helper==0.7.0 uses protobuf==5.29.6
ansys_tools_protoc_helper==0.6.0 uses protobuf==4.24.4

Start by locating the project's dependency declarations for ansys_tools_protoc_helper and inspect how its version is constrained. Add the requested upper bound below 0.7.0, then verify that dependency resolution selects ansys_tools_protoc_helper 0.6.0 and protobuf 4.24.4.

Written by the indexing model from the issue text.