Fix #517. iOS simulator pictures are PNG instead of JPEG

[DavidBertet]

Summary

Fix #517. iOS simulator pictures are PNG instead of JPEG

Use UIImageJPEGRepresentation instead of UIImagePNGRepresentation

How did you test this change?

• Run on iOS simulator iPhone 14 Pro
• Take a picture
• Check the output file

Before

> file 16EA62A2-A2EC-4A45-B453-A9BA464EF668-70523-0000038BA79327B9.jpg
16EA62A2-A2EC-4A45-B453-A9BA464EF668-70523-0000038BA79327B9.jpg: PNG image data, 1179 x 1752, 8-bit/color RGBA, non-interlaced

After

> file 70860A42-CC25-4FA3-AF27-F3DB397F6E2E-77443-0000039447870404.jpg
70860A42-CC25-4FA3-AF27-F3DB397F6E2E-77443-0000039447870404.jpg: JPEG image data, JFIF standard 1.01, aspect ratio, density 216x216, segment length 16, Exif Standard: [TIFF image data, big-endian, direntries=5, orientation=upper-left, xresolution=74, yresolution=82, resolutionunit=2], baseline, precision 8, 1179x1752, components 3

[scarlac]

Excellent! Thank you.