Format string extension is ignored when doing more than a single process

[Kuroonehalf]

• Video2X release version: 2.8.1
• GUI version: yes

Example of steps to reproduce:

• Import more than 1 GIF
• Set output file name format string to something like "{original_file_name}.mp4"
• Run conversion And the output will be in GIF form instead of MP4. If you run just a single GIF at a time the conversion to MP4 works, but if it's more than one it won't.

[k4yt3x]

Interesting... I'll fix this when GIF support is added in 5.0.0.