[fix] Fixed bug of incompatibility with gulp 5.

Author: Ulyanov-programmer

index.js

@@ -79,11 +79,12 @@ async function convert(file, newFileFormat, options) {
   if (newFileFormat == 'heif')
     options.compression = 'av1'
 
-  let sharpInstance =
-    sharp(file.contents, DEFAULT_SHARP_OPTIONS)
+  let sharpBuffer =
+    await sharp(file.path, DEFAULT_SHARP_OPTIONS)
       .toFormat(newFileFormat, Object.assign(DEFAULT_CONVERSION_OPTIONS, options))
+      .toBuffer()
 
-  return toVinyl(await sharpInstance.toBuffer(), newFileFormat, file)
+  return toVinyl(sharpBuffer, newFileFormat, file)
 }
 
 function toVinyl(buffer, newFileFormat, file) {