[nrktv] add additional URL scheme for episodes

[barsnick]

Series' episodes seem to have gained an additional URL scheme. This
expands the valid URL for NRKTVEpisodeIE.

A test was also added, but it fails due to a proper update of the
EPISODE_RE. (The existing test also fails, so d'uh.)

NRKTVSeriesIE may also need to be adapted.

Fixes #18304

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Add another URL scheme for episodes. Description above and in commit message.

[abdallahalsamman]

@dstftw This was not merged? can we know the reasoning behind closing without being merging?

[barsnick]

@dstftw This was not merged? can we know the reasoning behind closing without being merging?

This was fixed with a commit similar to mine, not with a merge:
33cc1ea

Fine by me if it works. Will test later (but I assume the author already did).

[abdallahalsamman]

@barsnick cool, I hope it works 👍