webp格式无法修改导出格式

[greysam]

Version

eg: 0.3.1

Operating system (version and arch)

mac 14.5 (23F79)

Describe the bug

当源文件是webp的时候，导出格式设置为jpg/png，Apply all之后 导出格式还是显示 webp，除非在单个文件上修改。
当源文件是其他格式时，没有上述问题。
When the source files are webp, and exported format is set to jpg/png, even after Apply all, the exported format still stay as webp, unless files are set individually

Screenshot

Logs

[xianfei]

我Fork了这个项目并添加了这个功能，欢迎尝试：https://github.com/xianfei/Imagine-plus