move 'import pytest' into the test function
move 'import pytest' into the test function

avoids the "ImportError: No module named 'importlib_metadata'" when
the server loads the test_rpc_timeout.py module and the client
is running on Python 3.8

MSLNZ/msl-loadlib,MSLNZ/msl-loadlib,MSLNZ/msl-loadlib,MSLNZ/msl-loadlib,MSLNZ/msl-loadlib