test_postprocess: Avoid depending on network service for tests
test_postprocess: Avoid depending on network service for tests

The sublanguage detection is handled by a webservice; having the tests
fail because of network issues/service outages would be nice to aovid.
Some environments are even designed to run without network connectivity
(e.g. debian package builds).

This patch has been forwarded upstream for consideration.

Reference: https://github.com/spaam/svtplay-dl/pull/1261

olof/debian-svtplay-dl,olof/debian-svtplay-dl