Since no typing stubs are available for mbed_host_tests.py, mypy
errors out on mbedtls_test.py with
error: Skipping analyzing 'mbed_host_tests': found module but no type hints or library stubs
Ignore this import to get at least some benefit from mypy without
spending significant effort to write stubs.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>