[electrum] better handle timeouts in test_interface

Summary:
Tests are failing on CI because we don't catch the correct error for python < 3.10

badssl.com seems to be unresponsive, lately. If this keeps happening, this test should be removed to not slow down the test suite unnecessarily.

Test Plan: python -m electrumabc.tests.test_interface

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D14619