NinjaCentral fix (NZBGet)

This is a fix related to how NinjaCentral names their NZB files.
All their NZBs have a dash + four characters appended to the filename/name of the NZB.
A few examples: `-ASn1` `-xm98` `-s4n4` - and so on

This reg-ex/reg-ex-replace works by removing that part only. I've had this reg-ex in my clean.py script for quite a long time, and haven't observed any negative effects with using this, with a lot of different NZB indexers simultaneously. 

A reg-ex test:
https://regex101.com/r/KD8uqu/1

docs/Downloaders/NZBGet/scripts/Clean/Clean.py

@@ -54,6 +54,7 @@ fwp = re.sub('(?i)\[TGx\]-xpost\.nzb$', '.nzb', fwp)
 fwp = re.sub('(?i)\[ettv\]\.nzb$', '.nzb', fwp)
 fwp = re.sub('(?i)-WRTEAM\.nzb$', '.nzb', fwp)
 fwp = re.sub('(?i)-CAPTCHA\.nzb$', '.nzb', fwp)
+fwp = re.sub(r'(\-[^-.\n]*)(\-.{4})?\.nzb$', r'\1.nzb', fwp)
 if fwp:
   print('[NZB] NZBNAME=', fwp, sep='')