screenshot: improve jpeg very high quality to 91 (enables yuv444 instead of yuv420)

src/main.cpp

@@ -2310,7 +2310,7 @@ static int video_quality_to_image_quality_value(gsr_video_quality video_quality)
         case GSR_VIDEO_QUALITY_HIGH:
             return 85;
         case GSR_VIDEO_QUALITY_VERY_HIGH:
-            return 90;
+            return 91;
         case GSR_VIDEO_QUALITY_ULTRA:
             return 97;
     }