[python-pytrakt] Add show_id attribute to TVEpisode found from search

[simonc56]

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Actually, to get the show of a TVEpisode we only have show name (self.show) which is not reliable because some shows have the same name. The show trakt id is more reliable than show name because it is unique. This PR adds show_id attribute to TVEpisode built from search request and uses it in further API requests instead of slug built from show name.

Example : Top Boy and Top Boy 2019 A TVEpisode from Top Boy 2019 uses slug top-boy (made from slugify(self.show) ) instead of top-boy-2019 to fetch data from trakt api. Therefore data received is wrong.

[glensc]

Carried to my fork:

• https://github.com/glensc/python-pytrakt/commit/dece4d0a1b453412f9e7f92a938232487977bffd

[glensc]

@twolaw please prepend [python-pytrakt] to this pr title, to indicate this pr has been carried. this will help understand the pull request status in this project.