Fix flaky test `tests/test_iotedgedev_solution.py::test_push_modules_to_local_registry`

[beandrad]

• iotedgedev Version: v3.3.4
• Python Version: 3.6
• Pip Version:
• Development machine OS Version: Ubuntu 20.04
• IoT Edge device OS Version: Ubuntu 20.04

This test fails from time to time when trying to push to the local registry:

ERROR: Get "[http://localhost:5000/v2/"](http://localhost:5000/v2/%22): read tcp [::1]:37004->[::1]:5000: read: connection reset by peer.

See pipeline run.

Steps to Reproduce:

1. Run the corresponding test.