fix: remove trim _pxx

[cokemine]

This should fix for some pictures titled end with _xxx, e.g. https://www.pixiv.net/artworks/100345141

リコリス・リコイル_02.txt shouldn't be trimed to リコリス・リコイル.txt

However, I don't know why info_filename = re.sub(r'_p?\d+$', '', info_filename) code exists. I checked the commit history and found that this was added six years ago, I think it may be a historical problem

[Nandaka]

it is for manga images, if you don't remove it, the info file will contains _pxx

[cokemine]

I 've tested both single image and manga images. I found that deleting this code did not change the output(except the bug that I mentioned), that's why I have that question

[cokemine]

I used the default config

filenameFormat = %artist% (%member_id%)/%urlFilename% - %title%
filenameMangaFormat = %artist% (%member_id%)/%urlFilename% - %title%
filenameInfoFormat = %artist% (%member_id%)/%urlFilename% - %title%
filenameMangaInfoFormat = %artist% (%member_id%)/%urlFilename% - %title%

info_filename is end with %title%, and _pxx will be only trimed from %title% not from %urlFilename%

So all the manga information will be in the format id_pXX - title and _pXX won't be trimed