Exporting as PFM applies postprocessing even if set to None

[Peregrine05]

When exporting the render to PFM, Chunky always exports the render with the Gamma correction postprocessing filter applied. Setting the filter to None or any other setting still makes Chunky export the PFM with Gamma correction. Using ShirleyNeko's ImageMagick plugin will allow exporting of PFM files without postprocessing.

[ShirleyNekoDev]

Discussion can be found here: https://discord.com/channels/541221265512464394/545374333883777037/981570248358658078