DEV: depend less on pngquant version (#26906)

This spec has been failing forever on my machine. I guess I have a "better" version of pngquant?

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Co-authored-by: Jarek Radosz <jradosz@gmail.com>

spec/lib/upload_creator_spec.rb

@@ -135,12 +135,12 @@ RSpec.describe UploadCreator do
           UploadCreator.new(file, filename, pasted: true, force_optimize: true).create_for(user.id)
 
         # no optimisation possible without losing details
-        expect(upload.filesize).to eq(9202)
+        expect(upload.filesize).to be_between(1000, 9210)
 
         thumbnail_size = upload.get_optimized_image(upload.width, upload.height, {}).filesize
 
         # pngquant will lose some colors causing some extra size reduction
-        expect(thumbnail_size).to be < 7500
+        expect(thumbnail_size).to be_between(1000, 7500)
       end
     end