Incorrect extension if file is not re-compressed

[savchenko]

Describe the bug
With the option "Skip if output size is bigger than the original" checked, the resulting file always has an extension selected in the "Format" drop-down menu.

Software version
v2.5.1

Operating System information

• Windows 10 22H2

To Reproduce
Steps to reproduce the behavior:

1. Set output file type to JPEG
2. Try to compress some vector which is obviously smaller in PNG
3. Observe original PNG being copied with JPEG extension into destination folder

Expected behavior
Keep original extension if file is unchanged.

Screenshots

Application Log

[2023-10-08 00:27:38.328][I] ---- Starting application ----
[2023-10-08 00:27:38.329][I] UUID: "xxx-xxx-xxx-xxx-xxx"
[2023-10-08 00:27:38.485][I] Starting UI
[2023-10-08 00:28:17.328][I] Compression ended successfully.
Total images: 31 
Uncompressed size: "14.50 MB" 
Compressed size: "7.66 MB" 
Elapsed time: 1880 ms