fix: Update zurg's plex_update.sh post hook script

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The plex_update.sh script seems to be having issues populating the /storage/symlinks/real-debrid-blackhole/ directory, and the cp command was unable to find directories to create symbolic links from in certain circumstances:

cp: cannot stat '/storage/realdebrid-zurg/shows/The quick brown fox jumps over the lazy dog (x265 HEVC 10bit)/*': No such file or directory

In addition, I noticed a broken * (asterisk) symlink file was being created in the /storage/realdebrid-zurg/shows/ folder.

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With the changes in this pull request, we get output like this:

Detected update on: __all__/SHOW\ -\ Seasons\ 1\ to\ 25
Absolute path: /storage/realdebrid-zurg/__all__/SHOW\ -\ Seasons\ 1\ to\ 25
Symlinking /storage/realdebrid-zurg/__all__/SHOW - Seasons 1 to 25 to /storage/symlinks/real-debrid-blackhole/__all__/SHOW\ -\ Seasons\ 1\ to\ 25
Encoded argument: %2Fstorage%2Frealdebrid-zurg%2F__all__%2FSHOW+-+Seasons+1+to+25

In addition, I noticed /symlinks/real-debrid-blackhole/__all__/ was finally getting created and populated for me.

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This works for me when using debridmediamanager directly, while bypassing overseerr + riven.

Adding media via overseerr + riven still continues to work fine.